REST API. Boom. This is the classic one. Rest is like the old reliable pizza delivery guy of the internet. You send a request like get me all users and boom, it delivers clean JSON data to your app. It uses simple HTTP methods. Get for reading, post for sending, put for updating, delete for removing. Almost every website you use, Instagram, YouTube, Twitter, runs on REST. It's simple, predictable, and easy to debug. But here's the catch. Sometimes REST gives you too much data, even stuff you don't need. Let me fix that with the next one. GraphQL. GraphQL said, "Rest, you're cool, but I want control." With GraphQL, you ask exactly for what you want. Nothing more, nothing less. Like, hey API, just give me the username and profile picture. And boom, it gives exactly that. It's super efficient, especially for big apps with lots of data used by Facebook, GitHub, and Shopify. Basically, REST gives you the full buffet. GraphQL gives you your custom meal. SOAP API. Soap, the old school business guy in the suit. It's super strict and uses XML instead of JSON. You'll find it in banking, insurance, or government systems. Anywhere reliability and security matters most. It's slower and more complicated, but man, it never breaks rules. Think of SOAP like an old bank server. Slow, but trustworthy. GRPC. Now meet gRPC, Google's speed monster. It's like REST, but it speaks binary instead of JSON, which makes it insanely fast for microervices. Small programs talking inside big systems. So instead of waiting for data like REST does, GPRGC just zips it over in lightning speed used in big tech systems where every millisecond counts. Boom. Performance mode on. Web hooks. Let me fix a big misunderstanding here. A web hook isn't you calling an API, it's the API calling you. It's like saying, "Hey, API, notify me when something happens." For example, when someone buys your product, the payment system calls your app automatically to say, "Yo, order complete." You don't keep asking. It tells you first. Boom. Instant updates. Zero waiting. Websocket. All right. Now, imagine chatting or gaming online. That's not REST anymore. You can't keep hitting refresh for new messages. That's where websockets step in. They keep a live connection open between your app and the server. So the moment something changes, boom, data flies instantly both ways. No delays, no reloads, just pure realtime magic. Think WhatsApp, Discord, or online games. All websocket powered. And finally, Web RTC, the cool kid behind live calls and video chats. When you FaceTime, talk on Google Meet, or stream webcam to webcam, that's Web RTC. It connects devices directly browser to browser. No middleman server.