System calls are the boundary between user programs and the kernel. They are the mechanism by which user-space applications request services from the operating system — opening files, creating processes, allocating memory, and more. Understanding syscalls reveals how the OS enforces isolation and provides safe access to hardware.
Learn API versioning strategies: URL path, header, and query parameter approaches. Understand backward compatibility, deprecation practices, and migration patterns.
Compare GraphQL and REST APIs, understand when to use each approach, schema design, queries, mutations, and trade-offs between the two paradigms.
Rate limiting protects APIs from abuse. Learn token bucket, sliding window, fixed window algorithms and distributed rate limiting at scale.
Learn REST principles, resource naming, HTTP methods, status codes, and best practices. Design clean, maintainable, and scalable RESTful APIs.