# Application Programming Interface **Aliases:** API **Entity class:** Software interface ## Definition An **Application Programming Interface (API)** is a defined contract through which software systems request operations or exchange structured data. In federated law-enforcement systems, APIs and web services can expose selected records from authoritative sources without duplicating the full source database. ## Relationships - **historical example:** [[wiki/DHS Law Enforcement Information Sharing Service|LEIS/LEISS]]. - **modern platform:** [[wiki/Case Management and Analytics Platform|CMAP]]. - **governed by:** authentication, authorization, schema, logging, and purpose restrictions. ## Sources / Provenance - [NIST — API glossary](https://csrc.nist.gov/glossary/term/application_programming_interface)