eli5: When an app updates, how are people on the old version still able to use it?

Question

I know this isnt the case 100% of the time but could someone pls explain. sorry im dumb and bad at tech

In: 0

Answer 1

The way an app works is that there’s code that’s running on your phone and it sometimes sends messages to a server at the company if it needs to do something over the internet. So if you’re using Spotify and you want to play a song, your phone sends a message to a server at Spotify that’s says something like “get song: 5553426” and the server sends back a message with the data. When you update an app, some of the code that runs on your phone can change, but as long as the servers are still using the same message format, you can keep using an older version of the app.