A Custom Connector is a Power Platform tool that allows for the creation of your own API connections to integrate with services and applications that are not available as pre-built connectors. This enables you to extend the capabilities of Power Apps, Power Automate, and Power BI by connecting to virtually any web service. Custom Connectors can be configured using OpenAPI definitions or Postman collections, and they support authentication methods like API keys, OAuth 2.0, and more.