The term "grant type" in OAuth 2.0 refers to the way an application gets an access token. The authorization code flow is one of several types of grants defined by OAuth 2.0. This grant is used by both web applications and native applications to obtain an access token after a user authorizes the application. As opposed to most other grant types, it requires the application to first launch a browser to begin the process/flow. The process involves the following steps:

The application opens a browser to direct the user to an OAuth server.

Upon seeing the authorization prompt, the user approves the application's request.

Upon approval, the user is redirected back to the application with an authorization code in the query string.

Application exchange authorization codes for access tokens.