An API request used by an application that performs a task on behalf of a particular user. Where a task is carried out with user-to-server authentication it's shown on GitHub as having been done by a user via an application. For example, you might choose to create an issue from within a third-party application, and the application would do this on your behalf on GitHub. The scope of tasks an application can perform using a user-to-server request is restricted by both the app's and the user's permissions and access. The token used in a user-to-server request is acquired via OAuth.