Like for example a person created a photo app every android user used the app and millions used it as well so it became popular.
For example Google wanted to buy it for 2 billion dollars.
How would the person sell the app?
By giving them the software he coded?
Where does the app get stored? Besides on the app store and Itunes store.
Or maybe a person needs a server, then create a website so people could access the app from there, I've seen some apps that don't have websites they are just on Itunes and Google Play Store plus on the app store.