SIG is a type of image file format that can only be opened or edited by Broaderbund graphics. Since all SIG files are created by Broaderbund programs, including Print Master or PrintShop, non-Broaderbund software programs are unable to open these files. To open these files with other graphic software, the SIG file must first be converted to JPEG.
SIG files are commonly seen at the end of emails or on forums in usernames. As such, these files are commonly referred to as signatures. Some emails and message forums automatically attach SIG files at the end of every email or post. This prevents the poster or sender from having to retype all of the information contained in the signature every time. This is helpful for business employees that include their emails, names, professional titles and addresses in every email.
Oftentimes, email services, such as those provided by Google and Yahoo, allow users to upload multiple SIG files or make their own using online software. This allows users to create signatures for every occasion. For example, some people have a signature that they attach to personal emails that is different than the signature they attach to business emails. Users also have the option not to attach signatures at the end of an email.