Most frequent use of RAR extension is to store compressed information archived using RAR format. It is a proprietary compression format developed by Eugene Roshal. Compressing files is very useful when you want to transfer them over the internet since compression reduces amount of information to transfer. Also you may fit much more information on your PC hard drive if you compress information that you don't use.

A file with the extension .p7m (digitally encrypted message) stores encrypted e-mail message. P7M contains both the messages and any attachments in it. Encrypted P7M files are used to prevent unauthorized access to e-mails

LNK files are commonly known as Windows shortcuts. They are used to refer to local files or remote urls. To view information in LNK file in Windows you can press right mouse button on a LNK file and select Properties from popup menu.

The Portable Document Format (PDF) is the file format created by Adobe Systems in 1993 for document exchange. PDF is a fixed-layout format used for representing two-dimensional documents in a manner independent of the application software, hardware, and operating system. Each PDF file encapsulates a complete description of a 2-D document (and, with Acrobat 3-D, embedded 3-D documents) that includes the text, fonts, images, and 2-D vector graphics that compose the documents.

Temporary files may be created by computer programs for a variety of purposes; principally when a program cannot allocate enough memory for its tasks, when the program is working on data bigger than architecture's address space, or as a primitive form of inter-process communication.

You can open XLSX file using Microsoft Excel application. Microsoft Excel is similar to other spread sheet applications that can store information that can be edited and viewed on several platforms. You can run Microsoft Excel and open XLSX files on Mac and Windows through installed Microsoft Office applications.

File Extension CRDOWNLOAD is used by Google Chrome to temporarily store downloaded file information when file is being downloaded. Usually information in CRDOWNLOAD file is incomplete until file is downloaded.

Files with extension DWG are usually used to store two and thre dimensional data used in engineering. Typical examples of software which use this format is Autocad, IntelliCAD, Caddie and Open Design Alliance applications. DWG is short for drawing. The .bak (drawing backup), .dws (drawing standards), .dwt (drawing template) and .sv$ (temporary automatic save) files are also DWG files.

The .BIN/.CUE image file format was developed by Jeff Arnold for the CDRWIN program. An image consists of two files which contain binary data and metadata, respectively. The filenames typically match (e.g. image.bin and image.cue). The .BIN file contains an exact copy of all data stored on an optical disc in raw, unprocessed form but without any subchannel data. For this reason, some programs use the .RAW suffix for these files.

DAT file extension could represent following file types:

- Data file

- A data file extension used to designate an error message in a inbound internet email message (Microsoft Exchange Server v 5.0)

- WordPerfect Merge Data

- Extension used for some MPEG files

- Yahoo Messenger archive file

APK extension is used to deliver and install application software and middleware onto Google Android system. APK file contains compiled Android application code and all resources which are required by this code.

Office Open XML (also referred to as OOXML or Open XML) is an ISO/IEC standardized ZIP-compatible file format originally developed by Microsoft for representing spreadsheets, charts, presentations and word processing documents. Starting with Microsoft Office 2007, the Office Open XML file formats (ECMA-376) have become the default file format of Microsoft Office.