API Key

A unique identifier used to authenticate requests, track usage, and control access between software applications.

API keys function as digital passports for software communication. They allow a service provider like Stripe or AWS to identify the calling application and enforce specific rate limits (e.g., 100 requests per second). By embedding a 32-character string in the HTTP header, developers bypass complex handshake protocols for simple, stateless authentication. While not a replacement for OAuth in high-security user data scenarios, they remain the industry standard for securing public data endpoints and managing developer quotas.

https://cloud.google.com/docs/authentication/api-keys