About ssh-agent commands and messages(Help topic)

[digo_katayama]

Hi guys,
Those anyone knows what these commands and messages means when I type
ssh-agent

$ ssh-agent

SSH_AUTH_SOCK=/tmp/ssh-OqdW7921/agent.7921; export SSH_AUTH_SOCK;

SSH_AGENT_PID=7922; export SSH_AGENT_PID;

echo Agent pid 7922;

thanks