Can you list components of Android that are not considered key?

The key components of Android are Activity, Service, Broadcast Receiver, and Content Provider. They provide the main functions of the application.

Non-key components are auxiliary elements that are not essential for the operation of the application but can be used to enhance functionality or development convenience. These include:

• Fragments — allow creating flexible interfaces but are not mandatory.
• View and ViewGroup — user interface elements.
• Helpers, utilities, and data-handling classes that do not inherit from the key components.
• Content Observer — for monitoring data changes.

Thus, non-key components are all other classes and elements that help build the application but are not part of the core Android architecture.