Why You Need to Understand APIs
The client or frontend needs to talk to the server. In essentially every case, the server exposes a set of functions it can perform via an API—that's the interface between them. You need to understand what an API is and how these are built, because APIs expose what functionality the server can offer to the client.
REST API Fundamentals
The most basic API you'll use in system design interviews is REST APIs. Master these first—they're what you'll rely on most of the time. Make sure you understand:
- HTTP verbs — GET, POST, PUT, PATCH, DELETE and when to use each