@flesh @benjojo Basically it's a special format to store encrypted passwords that lets you specify the algorithm and various parameters. Among other things, it lets you do things like on-the-fly algorithm upgrades for password hashing:
https://en.wikipedia.org/wiki/Crypt_(C)#Key_derivation_functions_supported_by_crypt
And yeah, as Lillian pointed out, this means that they're storing some (most?) passwords in plain text.