diff --git a/README.md b/README.md
index ce84870..4cea30d 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,12 @@
-# Package Name
-...
+# exchange-calendars-extensions-api
+This package contains parts of the API of 
+[exchange-calendars-extensions](https://pypi.org/project/exchange-calendars-extensions/).
+
+To separate the API from the implementation, the API is defined in a separate distribution package 
+[exchange-calendars-extensions-api](https://pypi.org/project/exchange-calendars-extensions_api/), i.e. this package, 
+that contains the sub-package `exchange_calendars_extensions.api`.
+
+The implementation has been moved to the sub-package `exchange_calendars_extensions.core` and is distributed via 
+[exchange-calendars-extensions](https://pypi.org/project/exchange-calendars-extensions/).
+
+The package `exchange_calendars_extensions` is now a namespace package that wraps the sub-packages.