Extension: dat
What is it? Data File
Where’s it from? Many programs create dat files. The location of a dat file may give you a clue as to which program created it. A dat file in a subfolder under a program’s folder was probably created by that program. INDEX.DAT is a special file created by Windows. It contains data on the Web sites you visit and the email you send. If you want to look at what Windows is tracking in the INDEX.DAT file, and possibly delete such files, try the free Index.dat Suite utility.
How do I use it? Let the program that created the dat file use it.
Can I safely delete or move it? Doing so may confuse the creating program, but won’t damage your computer.
Can it be dangerous? Not by itself, but a dat file may be used by malicious software.
–David Hakala
Extension: 7z
What is it? 7-Zip Compressed File
Where’s it from? 7z is an open source compressed file standard developed by the 7-Zip Organization. It supports compression/decompression of 7z, ZIP, GZIP, BZIP2 and TAR compressed files. It also supports decompression-only of ARJ, CAB, CHM, CPIO, DEB, DMG, HFS, ISO, LZH, LZMA, MSI, NSIS, RAR, RPM, UDF, WIM, XAR and Z. For ZIP and GZIP formats, 7-Zip provides a compression ratio that is 2-10 percent better than the ratio provided by PKZip and WinZip.
How do I use it? Use the 7-Zip archiver utility downloaded from the link above.
Can I safely delete or move it? Yes.
Can it be dangerous? Yes. Any compressed file can contain malware. Use an antivirus program.
–David Hakala
Extension: thm
What is it? OpenOffice.org 1.1.x Configuration File
Where’s it from? Thm files are created and used by the free Open Office v1.1x office productivity suite. Open Office is a free, open source alternative to the pricey Microsoft Office suite. Thm files contain information about user preferences, such as word processor page layouts.
How do I use it? Set your preferences in Open Office and it will take care of the thm files.
Can I safely delete or move it? Yes, but you will lose your Open Office preferences.
Can it be dangerous? No malware has been reported to exploit thm files.
–David Hakala
Extension: wmv
What is it? Windows Media Video File
Where’s it from? Audio/video file format developed by Microsoft. Many authoring programs can create wmv files.
How do I use it? Windows: Media Player; Mac: Quicktime, with Windows Media Components for Quicktime; Linux: MPlayer, with WMV Codecs for MPlayer
Can I safely delete or move it? Yes.
Can it be dangerous? Yes. Use antivirus software
–David Hakala
Extension: 3g2
What is it? 3GPP2 Multimedia File
Where’s it from? The 3g2 extension applies to both the 3GPP and 3GPP2 worldwide standards for multimedia files delivered over 3rd generation, high-speed wireless networks. These standards are defined by the 3rd Generation Partnership Project and 3rd Generation Partnership Project 2, respectively. They are based on the MPEG-4 standard which was derived from Apple’s QuickTime.
How do I use it? See your mobile device’s documentation to learn if it supports 3g2 files. Also, Apple Quicktime 6.5 and above supports 3g2 files.
Can I safely delete or move it? Yes.
Can it be dangerous? Yes. Multimedia files are “active content” which can execute embedded malware. 3g2 files should be scanned by antivirus software before use.
–David Hakala
Extension: tmp
What is it? Temporary File or Folder
Where’s it from? Tmp files are the scratch paper of many programs. Information needed during a program’s installation may be stored in a tmp file, never to be used again. Microsoft Word is famous for creating tmp files and not cleaning them up when you close the program.
How do I use it? There is no use for a tmp file. System maintenance utilities such as Advanced System Care ferret out and delete unnecessary tmp files, freeing up disk space.
Can I safely delete or move it? Yes.
Can it be dangerous? No.
–David Hakala
Extension: xpi
What is it? Mozilla Installer Package
Where’s it from? Xpi files are what you download to install a Firefox add-on (a. k. a., “extension”). They are compressed archive files designed to work specifically with Firefox on all its operating system platforms. Updates to Firefox are also delivered via xpi files.
How do I use it? You can launch the installation of an xpi file just by dragging and dropping it into a Firefox browser window, or double-clicking on it.
Can I safely delete or move it? Yes
Can it be dangerous? Yes. Use antivirus software
–David Hakala
Extension: kmz
What is it? Google Earth Saved Working Session
Where’s it from? Kmz files are created by the online Google Earth geographical information system (GIS). Google Earth is used to locate points on the planet and display satellite image information about locations.
How do I use it? Users don’t use kmz files. Google Earth accesses them when you are using it.
Can I safely delete or move it? Yes, but you will lose the file’s information about your saved Google Earth session. So you will have to start all over again or forget it.
Can it be dangerous? No malware has been reported that exploits kmz files.
–David Hakala
Extension: sys
What is it? Windows System file (most common)
Where’s it from? A sys file stores system settings and variables used by the Windows and MS-DOS operating systems. The information is stored in plain text and is often understandable by humans, i. e., PATH=C:\WINDOWS\SYSTEM32.
How do I use it? While it is possible to alter sys files using any text editor or word processor, only advanced users who really know what they’re doing should attempt it. The wrong edit can cause your computer not to start, or to crash unexpectedly.
Can I safely delete or move it? No.
Can it be dangerous? No.
–David Hakala
Extension: rar
What is it? WinRAR Compressed Archive File
Where’s it from? WinRAR, a popular Windows file compression and archiving program.
How do I use it? WinRAR is explained at the RARLAB Web site.
Can I safely delete or move it? Yes.
Can it be dangerous? Yes. Use antivirus software on any archive file before opening it.
–David Hakala
Powered by WordPress