So once you have created your own app, how would people get it or how would they buy it? You would need to upload your app onto Google Play Store. Google play store is a marketplace for android apps. Almost all of the android phones have it preinstalled from where they can download and install app.
To be able to upload apps on the play store, you need to have a developer account. It is a paid account and it costs 25$ as a onetime fee.
In order to upload an app to the play store, you need its installable file. This file is of the format .apk. All of your code and resources (images, fonts etc.) are bundled into this file. In order for Google to accept your app submission, it needs to be a signed .apk file. In short, signing is a process in which your signature (which is a key or a sort of password) is embedded inside the .apk file so that Google knows it is genuine and has come from you.
The final step is to actually go the Google play developer console and upload the app. Before uploading, you have to create a listing for your app on the console. You need to fill in relevant details like the app’s name, description etc. and upload some screenshots of your app. The complete process is explained here.
