Backup File Type

• A backup file contains a copy of all the information in an original file; if something goes wrong, the original can be restored instead of starting over from scratch. There are many types of backup files, including those stored on remote systems, on CDs or other portable devices.
  
  

Sage Applications

• The Sage Group is a supplier of business management software. In addition, this company provides support for all software it sells. The file extension .999 is associated with a number of Sage applications; a file with extension .999 is a backup file for the Sage application it is associated with.
  
  

Various-Data File Type

• File extension .999 can also signify a various-data file type when associated with the Multipass program. However, the file type is from an older version of the program and is no longer supported in newer versions.
  
  

Multipass Security File

• Multipass was documentation and code designed to encrypt a list of user names and passwords for use in an .htaccess file. A file with a .999 extension was part of the security files used with the program.
  
  

Identification of File Type

• If you know you have either Multipass or a Sage application installed, you can safely assume that the file is associated with the installed program. Otherwise, look at the file's image icon: If it looks like a blank piece of paper, it is a various-data file. If it looks like a yellow/gold disk, it is a backup file.