What is "api-key"

Web Applications: API Keys can be provided as JSON Web Tokens (JWT) via cookies or HTTP headers; in back-end operations, they can be part of the original URI of the request. Desktop applications: Keys API can be used to access the functionality of a third-party library. The sense of public or private API key also depends on the implementation. For example, you may have a public key issued to your client (say www.app.com) that allows access to a specific API (api.servico.com), which is then used by your browser. However server-to-server calls use another private key for more sensitive operations such as authentication and credential validation.