This is a web-based client for the Finger protocol, as defined in RFC 742 and RFC 1288.
Enter a query in the usual @host or user@host format, optionally prefixing with /W (or -l) to request "Whois" output (aka "finger -l" mode), e.g. /W @example.com. (Many hosts automatically assume you want the multi-line output when a username is specified, but not all do.)
Examples:
@athena.dialup.mit.edu,
@tilde.club,
or grawity@nullroute.lt.