diff --git a/knowledge_verificator/backend.py b/knowledge_verificator/backend.py
index bf0baac..e739c95 100644
--- a/knowledge_verificator/backend.py
+++ b/knowledge_verificator/backend.py
@@ -5,10 +5,10 @@
 from fastapi import FastAPI, Response
 
 from knowledge_verificator.materials import Material, MaterialDatabase
-from knowledge_verificator.io_handler import config
+from knowledge_verificator.io_handler import get_config
 
-endpoints = FastAPI()
-material_db = MaterialDatabase(materials_dir=config.learning_materials)
+ENDPOINTS = FastAPI()
+MATERIAL_DB = MaterialDatabase(materials_dir=get_config().learning_materials)
 
 
 def format_response(data: Any = '', message: str = '') -> dict:
@@ -38,7 +38,7 @@ def format_response(data: Any = '', message: str = '') -> dict:
     }
 
 
-@endpoints.get('/materials')
+@ENDPOINTS.get('/materials')
 def get_materials(
     response: Response, criteria: Union[str, None] = None
 ) -> dict:
@@ -58,10 +58,10 @@ def get_materials(
         response.status_code = 501
         return format_response(message=message)
     response.status_code = 200
-    return format_response(data=material_db.materials)
+    return format_response(data=MATERIAL_DB.materials)
 
 
-@endpoints.get('/materials/{material_id}')
+@ENDPOINTS.get('/materials/{material_id}')
 def get_material(material_id: str, response: Response):
     """
     Get a specific learning material.
@@ -74,7 +74,7 @@ def get_material(material_id: str, response: Response):
         dict: Under `data` key, there are `material_id` and `material` keys.
     """
     try:
-        material = material_db[material_id]
+        material = MATERIAL_DB[material_id]
     except KeyError:
         message = f'Material with id = {material_id} was not found.'
         response.status_code = 404
@@ -85,10 +85,10 @@ def get_material(material_id: str, response: Response):
     return format_response(data=data)
 
 
-@endpoints.post('/materials')
+@ENDPOINTS.post('/materials')
 def add_material(material: Material, response: Response) -> dict:
     """
-    Endpoint to add a learning material to a database.
+    Endpoint to add a learning material to the database.
 
     Args:
         material (Material): Learning material to be added.
@@ -101,7 +101,7 @@ def add_material(material: Material, response: Response) -> dict:
     response.status_code = 200
     message = ''
     try:
-        material_db.add_material(material=material)
+        MATERIAL_DB.add_material(material=material)
     except (ValueError, FileExistsError) as e:
         message = str(e)
         response.status_code = 400
@@ -110,13 +110,15 @@ def add_material(material: Material, response: Response) -> dict:
         return format_response(message=message)
 
     data = {'material_id': material.id}
-    return format_response(data=data)
+    return format_response(
+        data=data, message=f'Added the material with id = {material.id}.'
+    )
 
 
-@endpoints.delete('/materials/{material_id}')
+@ENDPOINTS.delete('/materials/{material_id}')
 def delete_material(material_id: str, response: Response) -> dict:
     """
-    Endpoint to delete a learning material.
+    Endpoint to delete a learning material from the database.
 
     Args:
         material_id (str): ID of the material to be removed.
@@ -127,11 +129,41 @@ def delete_material(material_id: str, response: Response) -> dict:
         of the removed material.
     """
     try:
-        material_db.delete_material(material=material_id)
+        MATERIAL_DB.delete_material(material=material_id)
     except KeyError as e:
         message = str(e)
         response.status_code = 400
         return format_response(message=message)
 
     response.status_code = 200
-    return format_response(data=str(material_id))
+    return format_response(
+        message=f'Deleted the material with id = {material_id}.'
+    )
+
+
+@ENDPOINTS.put('/materials')
+def update_material(material: Material, response: Response) -> dict:
+    """
+    Endpoint to update multiple attributes of a learning material
+    in the database.
+
+    Args:
+        material_id (str): ID of the material to be removed.
+        response (Response): Response to a request. Automatically passed.
+
+    Returns:
+        dict: Under `data` key, there is `material_id` key containing ID
+        of the removed material.
+    """
+    try:
+        MATERIAL_DB.update_material(material)
+    except KeyError as e:
+        message = str(e)
+        response.status_code = 404
+        return format_response(message=message)
+
+    response.status_code = 200
+    return format_response(
+        message=f'Updated the material with id = {material.id}.',
+        data=MATERIAL_DB[material.id],
+    )
diff --git a/knowledge_verificator/command_line.py b/knowledge_verificator/command_line.py
index dc359cc..e7ed678 100644
--- a/knowledge_verificator/command_line.py
+++ b/knowledge_verificator/command_line.py
@@ -2,7 +2,7 @@
 
 from rich.text import Text
 
-from knowledge_verificator.io_handler import logger, console, config
+from knowledge_verificator.io_handler import logger, console, get_config
 from knowledge_verificator.answer_chooser import AnswerChooser
 from knowledge_verificator.materials import MaterialDatabase
 from knowledge_verificator.nli import NaturalLanguageInference, Relation
@@ -45,6 +45,7 @@ def run_cli_mode():
     qg_module = QuestionGeneration()
     ac_module = AnswerChooser()
     nli_module = NaturalLanguageInference()
+    config = get_config()
 
     while True:
         options = ['knowledge database', 'my own paragraph']
diff --git a/knowledge_verificator/io_handler.py b/knowledge_verificator/io_handler.py
index 06e6d56..f918225 100644
--- a/knowledge_verificator/io_handler.py
+++ b/knowledge_verificator/io_handler.py
@@ -1,15 +1,19 @@
 """
-Module handling Input/Output, including parsing CLI arguments, provding
+Module handling Input/Output, including parsing CLI arguments, providing
 an instance of `rich` console, and an instance of a preconfigured `Logger`.
 """
 
 from argparse import ArgumentParser
+from functools import cache
 from logging import Logger
 from pathlib import Path
 from rich.console import Console
 from rich.logging import RichHandler
 
-from knowledge_verificator.utils.configuration_parser import ConfigurationParser
+from knowledge_verificator.utils.configuration_parser import (
+    Configuration,
+    ConfigurationParser,
+)
 
 
 def get_argument_parser() -> ArgumentParser:
@@ -39,16 +43,27 @@ def get_argument_parser() -> ArgumentParser:
     return arg_parser
 
 
-console = Console()
-logger = Logger('main_logger')
+@cache
+def get_config() -> Configuration:
+    """
+    Get configuration of the system.
 
-_logging_handler = RichHandler(rich_tracebacks=True)
+    Returns:
+        Configuration: Instance of configuration.
+    """
+    _parser = get_argument_parser()
+    args = _parser.parse_args()
 
-_parser = get_argument_parser()
-args = _parser.parse_args()
+    _configuration_parser = ConfigurationParser(configuration_file=args.config)
+    config = _configuration_parser.parse_configuration()
 
-_configuratioParser = ConfigurationParser(configuration_file=args.config)
-config = _configuratioParser.parse_configuration()
+    _logging_handler.setLevel(config.logging_level)
+    logger.addHandler(_logging_handler)
 
-_logging_handler.setLevel(config.logging_level)
-logger.addHandler(_logging_handler)
+    return config
+
+
+console = Console()
+logger = Logger('main_logger')
+
+_logging_handler = RichHandler(rich_tracebacks=True)
diff --git a/knowledge_verificator/main.py b/knowledge_verificator/main.py
index 092165b..6ddc84f 100755
--- a/knowledge_verificator/main.py
+++ b/knowledge_verificator/main.py
@@ -3,13 +3,13 @@
 from pathlib import Path
 import sys
 
-from knowledge_verificator.io_handler import config
+from knowledge_verificator.io_handler import get_config
 from knowledge_verificator.utils.configuration_parser import OperatingMode
 from knowledge_verificator.command_line import run_cli_mode
-from knowledge_verificator.backend import endpoints
 from tests.model.runner import ExperimentRunner
 
 if __name__ == '__main__':
+    config = get_config()
     match config.mode:
         case OperatingMode.EXPERIMENT:
             experiment_directory = Path(config.experiment_implementation)
@@ -24,7 +24,7 @@
             import uvicorn
 
             uvicorn.run(
-                endpoints,
+                'knowledge_verificator.backend:ENDPOINTS',
                 host='127.0.0.1',
                 port=8000,
                 reload=(not config.production_mode),
diff --git a/knowledge_verificator/materials.py b/knowledge_verificator/materials.py
index 406dae0..49ce84c 100644
--- a/knowledge_verificator/materials.py
+++ b/knowledge_verificator/materials.py
@@ -1,9 +1,9 @@
 """Module with tools for managing learning material."""
 
-from dataclasses import dataclass
+from dataclasses import dataclass, field
+import hashlib
 import os
 from pathlib import Path
-import uuid
 
 from knowledge_verificator.utils.filesystem import in_directory
 
@@ -14,11 +14,17 @@ class Material:
     Data class representing a learning material loaded from a database.
     """
 
-    path: Path
     title: str
     paragraphs: list[str]
-    tags: list[str]
-    id: str = str(uuid.uuid4())
+    tags: list[str] = field(default_factory=list)
+    path: Path | None = None
+    id: str = ''
+
+    def __eq__(self, value: object) -> bool:
+        if not isinstance(value, (Material)):
+            return False
+
+        return value.id == self.id
 
 
 class MaterialDatabase:
@@ -79,18 +85,22 @@ def load_material(self, path: Path) -> Material:
             content = ''.join(fd.readlines()).rstrip()
             paragraphs = content.split('\n\n')
 
-            return Material(
+            material = Material(
                 path=path.resolve(),
                 title=title,
                 paragraphs=paragraphs,
                 tags=tags,
             )
 
+            self._set_id(material)
+            return material
+
     def delete_material(self, material: Material | str) -> None:
         """
         Remove the first material matching the provided material with its `id`.
 
-        As `id` is actually universally unique identifier it should remove one item
+        As `id` is actually universally unique identifier,
+        it should remove one item.
 
 
         Args:
@@ -112,10 +122,22 @@ def delete_material(self, material: Material | str) -> None:
         index = self.materials.index(material)
         del self.materials[index]
 
+    def _title_to_path(self, title: str) -> Path:
+        title = title.replace(' ', '_')
+        title = title.replace('"', '')
+        title = title.replace("'", '')
+        return self.materials_dir.joinpath(title)
+
+    def _set_id(self, material: Material) -> None:
+        content = '\n\n'.join(material.paragraphs)
+        material.id = hashlib.sha256(
+            (material.title + content).encode(encoding='utf-8')
+        ).hexdigest()
+
     def add_material(self, material: Material) -> None:
         """
-        Add a learning material to a database, also material's its
-        representation  in a file.
+        Add a learning material to a database, also create material's
+        representation in a file.
 
         Args:
             material (Material): Initialised learning material without
@@ -131,11 +153,18 @@ def add_material(self, material: Material) -> None:
         """
         if not material.title:
             raise ValueError('Title of a learning material cannot be empty.')
+
+        self._set_id(material)
+
+        if material.path is None:
+            material.path = self._title_to_path(material.title)
+
         if material.path.exists():
             raise FileExistsError(
                 'A file in the provided path already exists. '
                 'Choose a different filename.'
             )
+
         if not in_directory(file=material.path, directory=self.materials_dir):
             raise ValueError(
                 f'A file {os.path.basename(material.path)}'
@@ -167,6 +196,52 @@ def _format_file_content(self, material: Material) -> str:
         return output
 
     def _create_file_with_material(self, material: Material) -> None:
+        if material.path is None:
+            raise ValueError(
+                f'Cannot create a material without a valid path. Current path: `{material.path}`.'
+            )
         with open(material.path, 'wt', encoding='utf-8') as fd:
             file_content = self._format_file_content(material=material)
             fd.write(file_content)
+
+    def update_material(
+        self, material: Material, ignore_empty: bool = True
+    ) -> None:
+        """
+        Update an existing learning material.
+
+
+        Args:
+            material (Material): Instance of learning material from the database.
+            ignore_empty (bool, optional): Do not update attribute with the
+                value equal to `None`. Defaults to True.
+
+        Raises:
+            KeyError: Raised if the learning material is not
+                present in the database.
+        """
+        if material not in self.materials:
+            raise KeyError(
+                f'Cannot update non-existent material: {str(material)}.'
+            )
+
+        index = self.materials.index(material)
+        old_path = self.materials[index].path
+
+        for _, attribute in material.__dataclass_fields__.items():
+            field_name = attribute.name
+            value = getattr(material, field_name)
+
+            if value is None and ignore_empty:
+                continue
+
+            index = self.materials.index(material)
+            original_material = self.materials[index]
+
+            setattr(original_material, field_name, value)
+
+        # If path is missing (not provided), use the old path.
+        if not material.path:
+            material.path = old_path
+        # Override a file with old material with the updated one.
+        self._create_file_with_material(material)
diff --git a/knowledge_verificator/utils/configuration_parser.py b/knowledge_verificator/utils/configuration_parser.py
index 4e96ba4..340ae03 100644
--- a/knowledge_verificator/utils/configuration_parser.py
+++ b/knowledge_verificator/utils/configuration_parser.py
@@ -63,7 +63,6 @@ def __init__(
             self.__setattr__(attribute, value)
 
         # Convert to a proper datatypes.
-        self.learning_materials: Path = Path(kwargs['learning_materials'])
         self.mode: OperatingMode = OperatingMode(kwargs['mode'])
         self.experiment_implementation = Path(
             kwargs['experiment_implementation']
diff --git a/knowledge_verificator/utils/filesystem.py b/knowledge_verificator/utils/filesystem.py
index bcbfc9c..810ed59 100644
--- a/knowledge_verificator/utils/filesystem.py
+++ b/knowledge_verificator/utils/filesystem.py
@@ -15,9 +15,9 @@ def in_directory(file: Path, directory: Path) -> bool:
     Returns:
         bool: Present in a directory or subdirectories (True) or not (False).
     """
-    return str(directory.resolve()) in str(
-        file.resolve()
-    ) and not file.samefile(directory)
+    directory_path = str(directory.resolve())
+    file_path = str(file.resolve())
+    return directory_path in file_path and directory_path != file_path
 
 
 def create_text_file(path: Path | str, content: str = '') -> None:
diff --git a/poetry.lock b/poetry.lock
index bc6144e..9827f56 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -2746,4 +2746,4 @@ files = [
 [metadata]
 lock-version = "2.0"
 python-versions = "^3.12"
-content-hash = "147f2537157ec9820556620585f198b9adc74fec900b2b670c5ffb484f159363"
+content-hash = "641d77274fd2ddc9a0668e8de2ed66bdf095a9b5cad190059b295c05a2cb7958"
diff --git a/pyproject.toml b/pyproject.toml
index ce78230..7af9251 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -16,6 +16,7 @@ tqdm = "^4.66.5"
 sentence-transformers = "^3.1.1"
 fastapi = {extras = ["standard"], version = "^0.115.2"}
 pyyaml = "^6.0.2"
+requests = "^2.32.3"
 
 [tool.poetry.group.test]
 
@@ -57,6 +58,11 @@ exclude = "tests/model/*"
 [tool.pytest.ini_options]
 addopts = "--cov=knowledge_verificator --cov-report html --cov-branch"
 
+[tool.coverage]
+exclude = [
+    "*/backend.py", # Backend tests exists but are not reported by coverage.
+]
+
 [build-system]
 requires = ["poetry-core"]
 build-backend = "poetry.core.masonry.api"
diff --git a/tests/software/test_config.yaml b/tests/software/test_config.yaml
new file mode 100644
index 0000000..d431a92
--- /dev/null
+++ b/tests/software/test_config.yaml
@@ -0,0 +1,6 @@
+mode: BACKEND
+logging_level: DEBUG
+production_mode: true
+learning_materials: ./test_database
+experiment_implementation: ./tests/model
+experiment_results: ./tests/model/results
diff --git a/tests/software/test_materials_database.py b/tests/software/test_materials_database.py
new file mode 100644
index 0000000..30a6628
--- /dev/null
+++ b/tests/software/test_materials_database.py
@@ -0,0 +1,212 @@
+"""Module with test for backend operations on the database of materials."""
+
+import json
+import multiprocessing
+import os
+from pathlib import Path
+import shutil
+import sys
+import time
+from typing import Any
+import pytest
+import requests  # type: ignore[import-untyped]
+import uvicorn
+import uvicorn.server
+
+SERVER = '127.0.0.1'
+PORT = 8000
+
+
+@pytest.fixture
+def database_directory():
+    """
+    Create a directory for test database during the setup,
+    and return path to it; remove the directory during the teardown.
+    """
+    directory = Path('test_database')
+    os.mkdir(directory)
+
+    yield directory
+    shutil.rmtree(directory)
+
+
+@pytest.fixture
+def mock_args(monkeypatch):
+    """
+    Simulate command-line arguments to prevent argparse from consuming
+    pytest's arguments.
+    """
+    temporary_test_config = 'tests/software/test_config.yaml'
+    monkeypatch.setattr(
+        sys, 'argv', ['knowledge_verificator', '-c', temporary_test_config]
+    )
+
+
+@pytest.fixture(autouse=True)
+def server(mock_args, database_directory):
+    """Set up and teardown the server with endpoints."""
+    process = multiprocessing.Process(
+        target=uvicorn.run,
+        args=('knowledge_verificator.backend:ENDPOINTS',),
+        kwargs={'host': SERVER, 'port': PORT, 'reload': False},
+    )
+    process.start()
+    # Wait for a server to start up.
+    time.sleep(2)
+
+    yield
+
+    process.terminate()
+    time.sleep(2)
+    process.kill()
+
+
+@pytest.fixture
+def material() -> dict[str, str | list]:
+    """Fixture to provide required fields to create a learning material."""
+    return {
+        'title': '123',
+        'paragraphs': ['123'],
+        'tags': ['123'],
+    }
+
+
+def send_request(
+    endpoint: str,
+    timeout: int = 15,
+    method: str = 'get',
+    request_body: Any = None,
+    expect_failure: bool = False,
+) -> tuple[dict, int]:
+    """
+    Wrapper for convenient requests sending.
+
+    Args:
+        endpoint (str): Name of the API endpoint.
+        timeout (int, optional): Maximum waiting time before closing
+            connection, in seconds. Defaults to 10.
+        method (str, optional): HTTP method, one of "get", "post", "put",
+            "delete", "patch". Defaults to 'get'.
+        request_body (Any, optional): Body of the HTTP request in JSON.
+            By default, None.
+        expect_error (bool, optional): If a failure is the expected behaviour.
+            If True, no exceptions are emitted for failed requests.
+
+    Returns:
+        tuple[dict, int]: Tuple with the decoded content of the response and
+            the HTTP status code.
+    """
+    url = f'http://{SERVER}:{PORT}/{endpoint}'
+    response = requests.request(
+        method=method,
+        url=url,
+        timeout=timeout,
+        json=request_body,
+        headers={'Content-Type': 'application/json'},
+    )
+    content = response.content.decode()
+    content = json.loads(content)
+    if response.status_code != 200 and not expect_failure:
+        raise ValueError(content)
+
+    return (content, response.status_code)
+
+
+def test_getting_empty_database(material):
+    """Test if the empty database returns no materials when requested."""
+    response, _ = send_request(
+        endpoint='materials',
+        method='get',
+    )
+    assert response['data'] == []
+    assert response['message'] == ''
+
+
+def test_adding_material(material):
+    """Test if a material"""
+
+    response, _ = send_request(
+        endpoint='materials',
+        method='post',
+        request_body=material,
+    )
+
+    assert response['data']['material_id'], 'Material id is empty.'
+
+
+def test_adding_and_removing_material(material):
+    """Test if a material may be added then removed."""
+
+    response, _ = send_request(
+        endpoint='materials',
+        method='post',
+        request_body=material,
+    )
+
+    assert response['data']['material_id'], 'Material id is empty.'
+
+    material_id = response['data']['material_id']
+    response, _ = send_request(
+        endpoint=f'materials/{material_id}',
+        method='delete',
+    )
+
+    assert response['message']
+
+
+def test_updating_material(material):
+    "Test if updating an existing material succeeds."
+
+    response, status_code = send_request(
+        endpoint='materials',
+        method='post',
+        request_body=material,
+    )
+
+    assert status_code == 200, 'Adding a new material to the database failed.'
+    assert response[
+        'data'
+    ][
+        'material_id'
+    ], 'Material id is missing in the response to adding a new material to the database.'
+
+    material_id = response['data']['material_id']
+    new_material = {
+        'id': material_id,
+        'title': 'Totally different title!',
+        'paragraphs': [],
+    }
+
+    response, status_code = send_request(
+        endpoint='materials',
+        method='PUT',
+        request_body=new_material,
+    )
+
+    assert status_code == 200, 'Updating an existing material failed.'
+    assert (
+        'Updated the material with id' in response['message']
+    ), 'Failed to update the material.'
+    assert (
+        new_material['title'] == response['data']['title']
+    ), 'Title of the material has not been updated.'
+
+
+def test_updating_non_existent_material_fails(material):
+    """Test if updating non-existent material fails."""
+
+    _, status_code = send_request(
+        endpoint='materials',
+        method='post',
+        request_body=material,
+    )
+
+    assert status_code == 200, 'Adding a new material to the database failed.'
+
+    _, status_code = send_request(
+        endpoint='materials/rand0m_byt3s',
+        method='delete',
+        expect_failure=True,
+    )
+
+    assert status_code != 404, 'Updating non-existent material cannot succeed.'