APIs (Application Programming Interfaces) enable the interaction between software systems, fostering enhanced features and capabilities across platforms. There are several types of APIs, each designed for specific use cases: Open APIs facilitate data access without exposing source codes, Partner APIs streamline B2B interactions, Internal APIs support intra-organizational communication, and Composite APIs unify data from multiple sources. Moreover, different API protocols such as REST, SOAP, GraphQL, Webhook, and RPC address various needs, offering different strengths like REST's scalability and SOAP's security. API request methods—GET, POST, PUT, DELETE, PATCH, and others—define how client applications interact with systems, each suitable for specific tasks such as data retrieval or resource updates. Understanding these API types, protocols, and methods is vital for developers to create effective, modern web applications tailored to their specific requirements and goals.