How do I push notifications on Android?

How can I send a test push notification on Android?

They can do a lot of things; for example, they can show the latest sports scores , get a user to take an action, such as downloading a coupon, or let a user know about an event, such as a flash sale. Push notifications look like SMS text messages and mobile alerts, but they only reach users who have installed your app.

Turn on notifications for Android devices