What an HTTP request actually is

The thing URLSession was sending

In Part I, every time the iOS app called APIClient, it used URLSession to send an HTTP request to http://localhost:8000 and got an HTTP response back. You never saw what that looked like on the wire — it was hidden behind Swift's Codable types. Time to open the envelope.

An HTTP request is just plain text sent over a network connection. No magic, no binary format — you could type one by hand with telnet if you wanted to.