# A

- [API (Application Programming Interface)](/glossary/a/api-application-programming-interface.md): A set of rules and definitions that allows software applications to communicate with each other, enabling the exchange of data and functionality.
- [API Endpoint](/glossary/a/api-endpoint.md): The point at which an API connects with the software program, allowing communication between systems.
- [API Gateway](/glossary/a/api-gateway.md): A tool that sits between clients and services, acting as a reverse proxy to accept all application programming interface (API) calls.
- [API Key](/glossary/a/api-key.md): A code passed in by computer programs calling an API to identify the calling program, its developer, or its user to the website.
- [API Rate Limiting](/glossary/a/api-rate-limiting.md): The practice of controlling the number of API requests a user can make within a specified time frame.
- [Asynchronous Operation](/glossary/a/asynchronous-operation.md): Operations that occur without waiting for the previous operation to complete, improving efficiency and performance.
- [Authentication](/glossary/a/authentication.md): The process of verifying the identity of a user or system.
- [Authorization](/glossary/a/authorization.md): The process of verifying what specific applications, files, and data a user has access to.