From the Solaris ftp manual:


Do not attempt "auto-login" upon initial connection.

If auto-login is not disabled, ftp checks the .netrc file in the user's home directory for an entry describing an account on the remote machine.

Just another dot file that can be in people's home directories. That is, if you don't have read access, you can still check if the file exists. It also saves time when using ftp, like .rhosts saves time with rlogin or rsh or rcp.