Gear, Software & Workflow
Application programming interface
Also called: API
Every third-party creator tool you use runs on one. The YouTube Data API is what lets an analytics dashboard show your view counts, a scheduler publish an upload at 9am, and a bulk editor rewrite a hundred descriptions while you make a coffee.
Quota is the detail that catches people. Each application gets a daily allowance of units and different calls cost different amounts, which is why a tool sometimes stops updating halfway through the day. Access to your channel is something you grant, and revoking it in your Google account settings cuts the tool off immediately.