Copyright 2005 Jonathan van Clute .sig, or “Dot Sig” as it’s affectionately known, stands for “Signature File” and is the text and (usually) other contact information placed at the bottom of email or other computer-based correspondence. It is traditionally used for things like phone numbers, alternate email addresses, mailing addresses, web site addresses, etc. However the real truth is, it can contain anything the author wishes to include. It is like having your very own piece of legitimate, .