RAR, DAT and BIN File Extensions RAR, DAT and BIN file extensions are very popular in computer world. At the same time only small amount of users knows that are they used for. File extension RAR stands for Roshal Archiver. In the same way PK in PKZip stands for Phil Katz. Storing information in a way we see it (words, paragraphs, pages) is very space inefficient. That is why computer scientists invented lots of multiple ways to compress the information. It is actually quite simple to understand who basic principle of compression works. For example if you have document which consists mostly of words "dog" and "cat" you can replace "dog" with "*" and "cat" with "+". Thus "dog chases cat" would look like "* chases +". As you see just by such simple operation we reduced length of the sentence by 4 characters. RAR actually uses much more advanced compression algorithm and often capable of reducing amount of stored information by 5-10 times. That is why it is so popular on the internet (it is much faster to download 1MB of information rather than 10MB). File extension DAT stands for DATA. This file extension is used by huge number of applications to store different helpful textual and binary information. Files with DAT extension usually tends to be quite huge. File extension BIN stands for BINARY. Binary is a way of representing information in a way which computer could more easily understand. You probably heard that computer doesn't count in a way we do from 1 to 10 but does it in a different way using binary systems where there only 2 digits - 0 and 1. So number 2 will be codes as 10, 7 as 111. So BIN files are usually used to store information coded in binary form which application could use during its work. Also I'd like to cover one bonus file extension since it became very popular in the age of internet. It is file extension XPI. This extension is used by Mozilla Firefox for installing Firefox extensions over the internet. This extension is pronounced "zippy" and the package contains instruction for Firefox on how to install the extension. If you have problems with any of the format above try finding an application which corresponds to your format. One more possibility is that you have a windows registry error. To check for registry errors you could download registry cleaner. Thank you for reading this article and I hope it is helpful to you. Please refer to my File Extension Guru site where you can find more details about file extension DAT and file extension RAR.