When you install an application on your Android phone, you are required to grant permissions to it in order for it to work properly.

Some of the permissions that you will have to grant are:

Camera: Used to take photos and videos

Microphone: Used to record audio

External storage: Used to store files

Account: Used to log in and register for an account

If you don't trust what an application does, or if you think that an app is using too much battery, or too much internet, you can automate the process to grant/revoke permissions and allow it to do something, only in the context you like.