API (Application Programming Interface)
An API (Application Programming Interface) is a set of rules, protocols, and tools that allow different software systems to communicate with each other. It defines how one application can access the functions or data of another without revealing its internal logic or implementation.
How It Works
An API acts as an intermediary between a client (an application, website, or service) and a server that provides data or functionality. When an application sends a request, the API processes it and returns a response in a standardized format — most commonly JSON or XML.
There are several main types of APIs:
- REST API — uses HTTP requests and is the most common in web development.
- SOAP API — based on XML and strict communication standards.
- GraphQL — allows clients to request only the specific data they need.
- WebSocket API — supports real-time, bidirectional communication.
Applications
APIs are used wherever systems need to interact: from mobile apps and websites to cloud platforms and enterprise systems. For example, APIs allow a CRM to access data from payment services or enable websites to integrate maps, authentication, and analytics tools.
Advantages
- Standardized data exchange and interoperability.
- Faster and simpler feature integration.
- Scalability and flexibility for development.
- Enhanced security — no direct access to internal system logic.
Example
An online store can use a payment provider’s API to process payments directly on its website. The system handles the request and returns a transaction confirmation without exposing customer data.
Frequently Asked Questions
An API enables software systems to exchange data and functions without direct access to each other’s source code, simplifying integration and development.
REST is simpler and faster, using HTTP and JSON, while SOAP relies on XML and strict standards, offering more formal and structured communication.
An API key is a unique identifier used to authenticate an application and manage access to API services.
APIs are used in online payments, maps, weather services, social networks, and mobile apps — connecting different platforms and data sources.
