Commonly monitored metrics in API analytics include response time (latency), error rates, and usage statistics. These metrics help assess the performance, reliability, and usage patterns of the API. Monitoring unrelated metrics like code complexity or marketing campaigns is not typically part of API analytics.

Performance testing is essential for APIs to guarantee that they respond quickly and efficiently to requests. This is crucial for a positive user experience and the success of applications that rely on the API.

API documentation provides comprehensive details about various aspects of the API, including endpoints, request/response formats, authentication mechanisms, and other API specifications. This information is essential for developers to understand how to use the API effectively.

Web APIs facilitate communication by allowing different software applications to share data and functionality through standardized protocols. This enables applications to interact and exchange information, making them more versatile and interconnected.

SQL Injection is a common vulnerability involving unauthorized commands being sent to a database via an API. Attackers can manipulate input data to execute malicious SQL queries, potentially gaining unauthorized access to the database and compromising the security of the API.

Rate limiting in conjunction with API keys is used to restrict the number of API requests that a single user or application can make within a specified time frame. This helps control excessive usage, protect against abuse, and ensure fair and efficient use of API resources.

RESTful APIs are considered Stateless because they do not maintain any information about previous requests. This architectural style allows each request from a client to be independent, enhancing scalability and performance.

Web APIs play a crucial role in "backend" development by allowing different software components to interact and share data. They enable the server-side logic of applications to communicate with databases, external services, and other software components.

Load testing is essential for APIs to ensure they can handle expected traffic loads without performance degradation. It helps identify bottlenecks, scalability issues, and performance limitations, ensuring that the API can deliver a seamless experience to users under varying loads.

OpenID Connect is built on top of OAuth and is used for user authentication. OAuth is a widely-used authorization protocol that allows third-party applications to access a user's resources without exposing their credentials. OpenID Connect extends OAuth to provide user authentication and allows applications to verify the identity of end-users.