System File Types
The System Files category includes files related to Mac, Windows, and Linux operating systems. Some examples include system libraries, icons, themes, and device drivers. Files output by the system are also included in this category.
Common system file extensions include .DLL, .DRV, .SYS, and .CAB.
| Extension | File Description | Popularity |
|---|---|---|
| .0 | Shared Library Link File | Uncommon |
| .000 | Indexing Service Data File | Rare |
| .386 | Windows Virtual Device Driver | Rare |
| .8xu | TI-83 Plus Operating System File | Uncommon |
| .adm | Administrative Template File | Average |
| .adml | Group Policy Language-Specific Administrative Template | Uncommon |
| .admx | Group Policy Administrative Template File | Average |
| .ani | Windows Animated Cursor | Common |
| .ann | Help Annotations | Uncommon |
| .aos | ARCHOS PCtablet Firmware File | Uncommon |
| .asec | Android Secure Application File | Average |
| .automaticdestinations-ms | Windows Jump List File | Uncommon |
| .bashrc | Bash Non-Interactive Login Shell File | Common |
| .bash_history | Bash History File | Common |
| .bash_profile | Bash Interactive Login Shell File | Common |
| .bio | BIOS File | Uncommon |
| .bk1 | Windows Indexing Service File | Rare |
| .bk2 | Windows Indexing Service Data File | Rare |
| .blf | CLFS Base Log File | Average |
| .bmk | Help Bookmarks | Uncommon |
| .bom | Mac OS X Bill of Materials File | Uncommon |
| .cab | Windows Cabinet File | Very Common |
| .cat | Windows Catalog File | Average |
| .cdmp | WCS Device Model Profile | Uncommon |
| .cgz | Linux Drivers Archive | Average |
| .chg | Windows Net Logon File | Uncommon |
| .chs | Windows Chinese Noise-Word List File | Rare |
| .cht | Windows Chinese Traditional Noise-Word List File | Rare |
| .ci | Windows Content Indexer Catalog File | Uncommon |
| .clb | COM+ Catalog File | Average |
| .cnt | Help Contents File | Average |
| .cpi | Codepage Information File | Average |
| .cpl | Windows Control Panel Item | Very Common |
| .cpr | Windows Phone Display Settings File | Average |
| .crash | Mac OS X Crash Log File | Average |
| .cur | Windows Cursor | Very Common |
| .dat | Windows Registry Hive File | Average |
| .desklink | Desktop Shortcut | Average |
| .deskthemepack | Windows 8 Desktop Theme Pack File | Average |
| .dev | Windows Device Driver File | Uncommon |
| .diagcab | Troubleshooting Pack Cabinet File | Average |
| .diagcfg | Troubleshooting Pack Configuration File | Uncommon |
| .diagpkg | Troubleshooting Pack File | Uncommon |
| .dit | Active Directory Information Tree File | Average |
| .dll | Dynamic Link Library | Very Common |
| .dlx | Renamed DLL File | Rare |
| .dmp | Windows Memory Dump | Very Common |
| .drv | Device Driver | Very Common |
| .dss | DCC Active Designer File | Uncommon |
| .dvd | DOS Device Driver | Rare |
| .dyc | Xerox Printer Driver Configuration File | Rare |
| .edj | Enlightenment Theme File | Common |
| .efi | Extensible Firmware Interface File | Average |
| .elf | Executable and Linkable Format File | Common |
| .emerald | Emerald Theme | Uncommon |
| .etl | Microsoft Event Trace Log File | Average |
| .evt | Windows Event Viewer Log File | Average |
| .evtx | Windows 7 Event Log File | Average |
| .ffa | Find Fast Status File | Uncommon |
| .ffl | Find Fast Document List | Uncommon |
| .ffo | Find Fast Document Properties Cache | Uncommon |
| .ffx | Microsoft Find Fast Index | Uncommon |
| .fid | Microsoft Catalog Indexing Service File | Rare |
| .fpbf | Mac OS X Burn Folder | Common |
| .ftg | Full Text Group | Uncommon |
| .fts | Full Text Search | Uncommon |
| .gmmp | WCS Gamut Map Model Profile | Uncommon |
| .grl | Windows Update Status File | Rare |
| .group | Windows Contacts Group File | Common |
| .grp | Windows Program Manager Group | Uncommon |
| .hdmp | Windows Heap Dump | Average |
| .help | Mac OS X Help Book | Average |
| .hhc | HTML Help Table of Contents | Average |
| .hhk | HTML Help Index | Average |
| .hiv | Windows Registry Hive File | Average |
| .hlp | Windows Help File | Common |
| .hpj | Help Project File | Average |
| .hsh | Windows Catalog Search Index File | Rare |
| .htt | Hypertext Template File | Average |
| .icl | Windows Icon Library File | Average |
| .icns | Mac OS X Icon Resource File | Common |
| .ico | Icon File | Common |
| .idx | Index File | Average |
| .ins | Internet Naming Service File | Uncommon |
| .ion | File Description File | Average |
| .ipod | Rockbox Firmware File | Uncommon |
| .itemdata-ms | Windows 8 Start Screen Item Data File | Average |
| .its | Internet Document Set | Rare |
| .job | Windows Task Scheduler Job File | Average |
| .jpn | Windows Japanese Noise-Word List File | Rare |
| .kbd | Keyboard Layout Script | Average |
| .kext | Mac OS X Kernel Extension | Average |
| .key | Security Key | Common |
| .ko | Linux Kernel Module File | Average |
| .kor | Windows Korean Noise-Words List File | Rare |
| .library-ms | Windows Library Description File | Average |
| .lnk | File Shortcut | Very Common |
| .lockfile | Mac OS X PLIST Lock File | Average |
| .log1 | Windows Registry Hive Log File | Average |
| .log2 | Windows Registry Hive Log 2 File | Average |
| .lpd | Lookout Protocol Driver File | Average |
| .lpd | LPD Daemon Print Permissions File | Uncommon |
| .lst | GRUB Boot List File | Average |
| .manifest | Windows Visual Styles File | Average |
| .mapimail | Send To Mail Recipient | Average |
| .mbr | Master Boot Record File | Uncommon |
| .mdmp | Windows Minidump | Average |
| .mem | Parallels Desktop Memory Dump File | Uncommon |
| .metadata_never_index | Spotlight Never Index File | Uncommon |
| .mi4 | Audio Player Firmware File | Average |
| .mlc | Microsoft Language Interface Pack | Average |
| .mobileconfig | Apple Mobile Configuration File | Average |
| .msc | Microsoft Management Console Snap-in Control File | Average |
| .msp | Windows Installer Patch | Common |
| .msstyle | Windows XP Unsigned Style | Uncommon |
| .msstyles | Windows XP Style | Average |
| .mui | Multilingual User Interface File | Average |
| .mum | Windows Vista Update Package | Average |
| .mydocs | Send To My Documents | Average |
| .nb0 | Device Boot Loader Image | Common |
| .nfo | System Information File | Average |
| .nls | Microsoft National Language Support File | Average |
| .nt | Windows NT Startup File | Average |
| .panic | Kernel Panic File | Uncommon |
| .pat | DiskStation Manager Installation File | Average |
| .pck | System Center Configuration Manager Package File | Common |
| .pdr | Windows Port Driver | Average |
| .pfx | PKCS #12 Certificate File | Common |
| .pid | Creative Driver File | Rare |
| .pk2 | Silkroad Online Game Data File | Average |
| .pnf | Precompiled INF File | Average |
| .pol | Windows Policy File | Average |
| .ppd | PostScript Printer Description File | Average |
| .ppm | Post Programmable Memory File | Uncommon |
| .prefpane | Mac OS X System Preference Pane | Average |
| .prf | Windows System File | Common |
| .printerexport | Windows Printer Migration File | Uncommon |
| .profile | Bash Shell Profile | Common |
| .prt | Printer Driver File | Rare |
| .ps1 | Microsoft Indexing Service Data File | Rare |
| .ps2 | Microsoft Search Catalog Index File | Rare |
| .pwl | Windows Password List | Average |
| .qvm | Q Virtual Machine | Rare |
| .rc1 | Samsung Mobile Device Firmware File | Uncommon |
| .rc2 | Samsung Mobile Device Firmware File | Uncommon |
| .rco | PlayStation Portable Resource File | Uncommon |
| .reg | Registry File | Common |
| .regtrans-ms | Registry Transaction Log File | Average |
| .rfw | Rockchip Firmware File | Average |
| .rmt | Router Firmware File | Average |
| .ruf | Samsung DVD and Blu-ray Player Firmware File | Rare |
| .savedsearch | Spotlight Saved Search | Average |
| .saver | Mac OS X Screen Saver | Average |
| .sbf | Android System File | Average |
| .sbn | Cisco IP Phone Firmware File | Average |
| .scap | EFI Firmware File | Uncommon |
| .scf | Windows Explorer Command | Common |
| .schemas | GConf Schema Definition File | Uncommon |
| .scr | Windows Screensaver | Common |
| .sdb | Custom Application Compatibility Database | Common |
| .searchconnector-ms | Windows Search Connector File | Average |
| .sfcache | ReadyBoost Cache File | Uncommon |
| .shd | Windows Print Job Shadow File | Average |
| .shsh | iPhone/iPod Touch SHSH Blob File | Average |
| .so.0 | Unix Shared Library File | Uncommon |
| .spl | Windows Print Spool File | Average |
| .sqm | Service Quality Monitoring File | Average |
| .str | Windows Screensaver File | Rare |
| .swp | Swap File | Uncommon |
| .sys | Motorola Driver File | Average |
| .sys | Windows System File | Very Common |
| .tha | Windows Thai Noise-Words List File | Rare |
| .theme | Microsoft Plus! Desktop Theme | Average |
| .vga | VGA Display Driver | Uncommon |
| .vgd | Generic CADD VGA Driver | Uncommon |
| .vxd | Virtual Device Driver | Average |
| .vx_ | Compressed Virtual Device Driver File | Uncommon |
| .wdf | Windows Driver Foundation File | Average |
| .wdgt | Dashboard Widget | Common |
| .webpnp | Web Point and Print File | Average |
| .wer | Windows Error Report | Uncommon |
| .wgz | S60 Web Runtime Widget Package | Average |
| .wph | Phoenix BIOS File | Average |
| .wpx | Printer Description File | Rare |
| .xrm-ms | Microsoft Security Certificate | Uncommon |
| .zone.identifier | Windows Zone Identifier File | Average |