The finger command is a client for the finger protocol. It is able to display information (GECOS) about user such as their full name, email address, and telephone numbers.
Additionally, a user can configure a .plan and .project file within their home directories that are displayed when someone looks them up using finger.
This can be used locally or over a network:
Locally:
finger daniel ### shows information about the local user named daniel
Remotely:
finger daniel@10.1.1.1 ### shows information about the user daniel on host 10.1.1.1