GitHub is kind of a cloud service, but it isn't a server host. Cloud development is just more…abstracted than traditional web development. Instead of controlling a computer and choosing how to store files and managing ports and firewalls and making backups and serving requests and redirecting to closer servers and making sure you have enough computing power but not too much computing power and all that stuff, you instead just give Amazon/Microsoft/Google your code and data and pay them to do all that for you.