OpenID Connect - Implicit Flow
Legacy browser-based flow where tokens are returned directly in the redirect URI fragment. Deprecated in favour of Authorization Code + PKCE.
The Implicit flow was designed for public Single-Page Applications without a back-end, before PKCE existed. It returns the ID token (and optionally an access token) directly in the fragment of the redirect URI.
While modern guidance recommends Authorization Code with PKCE, when used with Form Post response mode, Implicit Flow offers a simplified workflow if the application only needs an ID token to authenticate the user.