The .1 file extension is used by a variety of computer applications. It is commonly used by the File Splitter software to assign a number to a volume of a split file. This happens when a large archive file is created and the user wants to split the archive file down into smaller volumes. The .1 file extension is given to the first file of the split file archive.
The .1 file extension is also used by the Unix operating system when the system creates an unformatted manual page. In some cases Mozilla Firefox will also use the .1 extension, giving it to files that store data about cookie, image and pop-up permissions. AIM Messenger also uses the .1 extension for certain IM files.
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File.org aims to be the go-to resource for file type- and related software information. We spend countless hours researching various file formats and software that can open, convert, create or otherwise work with those files.
If you have additional information about the 1 file format or software that uses files with the 1 suffix, please do get in touch - we would love hearing from you.