diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/DocumentManager.kt b/core-api-library/library/src/main/java/net/gini/android/core/api/DocumentManager.kt
index c4c5baaa20..1e642da50e 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/DocumentManager.kt
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/DocumentManager.kt
@@ -9,7 +9,7 @@ import net.gini.android.core.api.models.SpecificExtraction
 import org.json.JSONObject
 
 /**
- * The [DocumentManager] is a high level API on top of the Gini API, which is used via the [DocumentRepository]. It
+ * The [DocumentManager] is a high level API on top of the Gini API, via which the [DocumentRepository] is used. It
  * provides high level methods to handle document related tasks easily.
  */
 abstract class DocumentManager<out DR: DocumentRepository<E>, E: ExtractionsContainer>(private val documentRepository: DR) {
diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/MediaTypes.java b/core-api-library/library/src/main/java/net/gini/android/core/api/MediaTypes.java
index fc39563e79..c19f0ecf82 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/MediaTypes.java
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/MediaTypes.java
@@ -1,9 +1,11 @@
 package net.gini.android.core.api;
 
-
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 
+/**
+ *  Media Types used across the application (e.g document types, http headers)
+ */
 public class MediaTypes {
 
     public static final String IMAGE_JPEG = "image/jpeg";
diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/Resource.kt b/core-api-library/library/src/main/java/net/gini/android/core/api/Resource.kt
index af35b376d4..b97ea15e89 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/Resource.kt
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/Resource.kt
@@ -4,7 +4,7 @@ import net.gini.android.core.api.requests.ApiException
 import java.util.concurrent.CancellationException
 
 /**
- * Represents a requested API resource. Resources can be requested successfully, with an error or they can be cancelled.
+ * Represents a requested API resource. Resource requests can be returned successfully, with an error or they can be cancelled.
  */
 sealed class Resource<T>(
     open val data: T? = null,
diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/internal/GiniCoreAPIBuilder.kt b/core-api-library/library/src/main/java/net/gini/android/core/api/internal/GiniCoreAPIBuilder.kt
index 79f2bc8935..97453da585 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/internal/GiniCoreAPIBuilder.kt
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/internal/GiniCoreAPIBuilder.kt
@@ -36,6 +36,16 @@ import javax.net.ssl.SSLContext
 import javax.net.ssl.SSLSocketFactory
 import javax.net.ssl.TrustManager
 
+/**
+ * The [GiniCoreAPIBuilder] allows you to build and configure a [GiniCoreAPI] instance.
+ *
+ * @constructor Initializes a new builder instance.
+ * @param context your application's Context instance (Android)
+ * @param clientId your application's client ID for the Gini Health API
+ * @param clientSecret your application's client secret for the Gini Health API
+ * @param emailDomain  the email domain which is used for created Gini users
+ * @param sessionManager if not null, then the [SessionManager] instance will be used for session management. If null, then anonymous Gini users will be used.
+ */
 abstract class GiniCoreAPIBuilder<DM : DocumentManager<DR, E>, G : GiniCoreAPI<DM,DR, E>, DR : DocumentRepository<E>, E : ExtractionsContainer>(
     private val context: Context,
     private val clientId: String,
@@ -107,6 +117,9 @@ abstract class GiniCoreAPIBuilder<DM : DocumentManager<DR, E>, G : GiniCoreAPI<D
         return this
     }
 
+    /**
+     * Differentiate between different types of GiniApi's.
+     */
     abstract fun getGiniApiType(): GiniApiType
 
     /**
diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/models/Box.java b/core-api-library/library/src/main/java/net/gini/android/core/api/models/Box.java
index bdaa4560e9..e45b62a9a3 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/models/Box.java
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/models/Box.java
@@ -7,6 +7,11 @@
 import org.json.JSONException;
 import org.json.JSONObject;
 
+/**
+ * The box where an extraction is found.
+ *
+ * Only available on some extractions.
+ */
 public class Box implements Parcelable {
     private final int mPageNumber;
     private final double mLeft;
diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/models/CompoundExtraction.java b/core-api-library/library/src/main/java/net/gini/android/core/api/models/CompoundExtraction.java
index cfc2dab882..c6c473583c 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/models/CompoundExtraction.java
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/models/CompoundExtraction.java
@@ -14,6 +14,8 @@
 import java.util.Map;
 
 /**
+ * A compound extraction describes a group of extractions.
+ *
  * Created by Alpar Szotyori on 13.02.2020.
  *
  * Copyright (c) 2020 Gini GmbH.
diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/models/Document.java b/core-api-library/library/src/main/java/net/gini/android/core/api/models/Document.java
index 0dcb0a16e0..65044c15b2 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/models/Document.java
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/models/Document.java
@@ -17,6 +17,9 @@
 import java.util.Date;
 import java.util.List;
 
+/**
+ * A document sent for processing to the Gini API.
+ */
 public class Document implements Parcelable {
 
     /**
diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/models/Extraction.java b/core-api-library/library/src/main/java/net/gini/android/core/api/models/Extraction.java
index 9aa9752511..0eed779595 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/models/Extraction.java
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/models/Extraction.java
@@ -6,6 +6,13 @@
 import android.os.Parcelable;
 import androidx.annotation.Nullable;
 
+/**
+ * An extraction contains an entity that describes a general semantic type of the extraction, such as iban, bic, or amount.
+ * The entity also determines the format of the value containing text information.
+ *
+ * There might be an optional box element describing the position of the extraction value on the document. We refer to it as the bounding box.
+ * In most cases, the extractions without a bounding box are considered to be meta information such as doctype.
+ */
 public class Extraction implements Parcelable {
     private String mValue;
     private final String mEntity;
diff --git a/core-api-library/library/src/main/java/net/gini/android/core/api/models/SpecificExtraction.java b/core-api-library/library/src/main/java/net/gini/android/core/api/models/SpecificExtraction.java
index dd343aab9c..c4aa5f4d54 100644
--- a/core-api-library/library/src/main/java/net/gini/android/core/api/models/SpecificExtraction.java
+++ b/core-api-library/library/src/main/java/net/gini/android/core/api/models/SpecificExtraction.java
@@ -9,6 +9,9 @@
 import java.util.ArrayList;
 import java.util.List;
 
+/**
+ * A specific extraction assigns a semantic property to the extraction. It also has an additional candidates field.
+ */
 public class SpecificExtraction extends Extraction {
 
     private final String mName;
diff --git a/health-api-library/library/src/main/java/net/gini/android/health/api/GiniHealthAPIBuilder.kt b/health-api-library/library/src/main/java/net/gini/android/health/api/GiniHealthAPIBuilder.kt
index e17f6d3779..5344e94422 100644
--- a/health-api-library/library/src/main/java/net/gini/android/health/api/GiniHealthAPIBuilder.kt
+++ b/health-api-library/library/src/main/java/net/gini/android/health/api/GiniHealthAPIBuilder.kt
@@ -38,9 +38,9 @@ class GiniHealthAPIBuilder @JvmOverloads constructor(
     }
 
     /**
-     * Builds the GiniBankAPI instance with the configuration settings of the builder instance.
+     * Builds the GiniHealthAPI instance with the configuration settings of the builder instance.
      *
-     * @return The fully configured GiniBankAPI instance.
+     * @return The fully configured GiniHealthAPI instance.
      */
     override fun build(): GiniHealthAPI {
         return GiniHealthAPI(createDocumentManager(), getCredentialsStore())
diff --git a/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/GiniHealth.kt b/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/GiniHealth.kt
index 97ed8b25f8..5c04ab1b3f 100644
--- a/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/GiniHealth.kt
+++ b/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/GiniHealth.kt
@@ -27,7 +27,7 @@ import java.lang.ref.WeakReference
 /**
  * [GiniHealth] is the main class for interacting with the Gini Health SDK.
  * It provides a way to submit a document for reviewing its extracted payment details and
- * let's the user make the payment with one of the payment providers.
+ * lets the user make the payment with one of the payment providers.
  *
  * The recommended flow is:
  *  1. Call one of the overloads of [setDocumentForReview], to submit a document.
diff --git a/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/ReviewFragment.kt b/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/ReviewFragment.kt
index 2b9a0847b4..544dcd94f9 100644
--- a/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/ReviewFragment.kt
+++ b/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/ReviewFragment.kt
@@ -63,7 +63,7 @@ import net.gini.android.health.sdk.bankselection.BankSelectionBottomSheet
 data class ReviewConfiguration(
     /**
      * If set to `true`, the [ReviewFragment] will handle errors internally and show snackbars for errors.
-     * If set to `false` errors will be ignored by the [ReviewFragment]. In this case the flows exposed by [GiniHealth] should be observed for errors.
+     * If set to `false`, errors will be ignored by the [ReviewFragment]. In this case the flows exposed by [GiniHealth] should be observed for errors.
      *
      * Default value is `true`.
      */
diff --git a/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/model/ExtractionResult.kt b/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/model/ExtractionResult.kt
index 0f81b8e900..e04c6f7c0e 100644
--- a/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/model/ExtractionResult.kt
+++ b/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/model/ExtractionResult.kt
@@ -2,9 +2,25 @@ package net.gini.android.health.sdk.review.model
 
 import net.gini.android.core.api.Resource
 
+/**
+ * Represents the result of processing a document to get its extractions.
+ * Wraps the result of the extraction request.
+ */
 sealed class ResultWrapper<out T> {
+
+    /**
+     * Request completed successfully and extractions were returned.
+     */
     class Success<T>(val value: T) : ResultWrapper<T>()
+
+    /**
+     * Request was unable to complete - returns the cause of the error
+     */
     class Error<T>(val error: Throwable) : ResultWrapper<T>()
+
+    /**
+     * Request did not complete yet.
+     */
     class Loading<T> : ResultWrapper<T>()
 }
 
diff --git a/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/model/PaymentDetails.kt b/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/model/PaymentDetails.kt
index be71d00bff..8fc86a391d 100644
--- a/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/model/PaymentDetails.kt
+++ b/health-sdk/sdk/src/main/java/net/gini/android/health/sdk/review/model/PaymentDetails.kt
@@ -8,6 +8,9 @@ import net.gini.android.core.api.models.SpecificExtraction
 import net.gini.android.health.sdk.review.error.NoPaymentDataExtracted
 import net.gini.android.health.sdk.util.toBackendFormat
 
+/**
+ * Represents the payment details of an invoice as extracted from a document.
+ */
 @Parcelize
 data class PaymentDetails(
     val recipient: String,
@@ -44,7 +47,7 @@ internal fun String.toAmount(): String {
 /**
  * Checks if the document is payable which looks for iban extraction.
  */
-val PaymentDetails.isPayable get() = iban.isNotEmpty()
+val PaymentDetails.isPayable get() = iban.isNotEmpty()  // It appears this is not used anymore - we could remove it at a later stage (would remove it from the documentation as well)
 
 internal fun MutableMap<String, CompoundExtraction>.withFeedback(paymentDetails: PaymentDetails): Map<String, CompoundExtraction> {
     this["payment"] = this["payment"].let { payment ->