Ruby on Rails

The Ruby on Rails Tutorial by Michael Hartl is the classic way to learn Rails. It builds a complete Twitter-like sample app with user signup, login, account activation, password resets, microposts and following, and teaches testing and deployment along the way. It is updated for new Rails versions and the online book is the main entry here.

For a shorter project, How To Build a Ruby on Rails Application from DigitalOcean sets up a small app with SQLite and walks through models, controllers and views. Build Instagram From Scratch with Ruby on Rails is a PDF hosted on Dropbox that builds a photo-sharing app, and Build a Social Network using Rails is a Medium tutorial on the same kind of app. Check the Rails version each tutorial targets, since older ones predate changes like Hotwire and import maps.