APIs and system communication

APIs let different systems talk to each other. When you order an Uber, your phone asks "what drivers are nearby?" The server responds with a list. When you book a ride, your phone sends your pickup location.

APIs work through requests and responses. Here are some examples:

• A GET request asks for information, like showing nearby drivers
• A POST request creates something new, like booking a ride
• A PUT request updates existing information, such as changing your pickup location
• A DELETE request removes something, like canceling a ride

These 4 request types are used in REST APIs, the most common type today because they use standard internet protocols. Other API types, like SOAP, follow different rules and structures for exchanging data.

Many companies make APIs available so other apps can use their services. For instance, weather apps rely on weather service APIs, and payment apps often use Stripe’s API instead of building their own payment system. Well-designed APIs are easy to use because they follow consistent patterns and have clear documentation.