An API (Application Programming Interface) is a standardized set of rules that allows different software systems to securely communicate and exchange data.
An API (Application Programming Interface) is a contract that lets software call other software: defined endpoints, request/response formats, authentication, and rate limits. AI APIs expose model capabilities over HTTPS: you send a prompt (plus parameters like temperature and max tokens) and receive generated output, with billing metered per token.
APIs are how 99% of teams access frontier AI: no GPUs, no model hosting, capability as a metered utility. API literacy (auth, streaming, error handling, rate limits, cost controls) is the entry skill of AI engineering, and API design choices shape every integration built on top.
A secret credential identifying and authorizing your application. Leaked keys mean stolen usage on your bill: store them in secret managers, never in client code or repositories, and rotate on any suspicion.
Caps on requests or tokens per time window that protect shared infrastructure. Production clients handle them with retries, backoff, and queuing, and architects design around them when planning throughput.
A proxy layer between your apps and model providers that centralizes authentication, logging, caching, failover across providers, and spend controls: standard 2026 architecture once multiple teams call AI APIs.