File extensions start with character 'B'
| File Type | Category | File Format | |
|---|---|---|---|
| .b | Basic Files | Grand Theft Auto 3 Saved Game File | |
| .b&w | Image Files | Atari Bitmap Image File | |
| .b1 | Compressed Files | B1 Compressed Archive | |
| .b4s | Audio Files | Winamp Playlist File | |
| .b_w | Image Files | Atari Monochrome Image File | |
| .ba | Backup Files | Scifer External Header Archive | |
| .backup | Backup Files | Android Backup File | |
| .bad | Definition Files | Exchange Badmail File | |
| .bafl | Data Files | BurnAware File List | |
| .bak | Backup Files | Backup File | |
| .band | Audio Files | GarageBand Project File | |
| .bap | Audio Files | Blaze Audio Wave Information File | |
| .bar | Archive Files | Age of Empires 3 Data File | |
| .bat | Program Execution Files | DOS Batch File | |
| .bbb | Backup Files | BlackBerry Mobile Phone Backup File | |
| .bbl | Partially Downloaded Files | BibTeX Generated Bibliography File | |
| .bbp | CAD Files | Bézier Surface file | |
| .bbs | Text Files | Bulletin Board System Text | |
| .bc | Partially Downloaded Files | BitComet Partially Downloaded File | |
| .bc! | Multiple Use Files | BitComet Incomplete File | |
| .bcc | Data Files | Calendar Creator File | |
| .bcd | System Files | Windows Boot Configuration Data File | |
| .bci | Data Files | Belarc Advisor Report File | |
| .bck | Backup Files | VMX Backup File | |
| .bcm | Data Files | Business Contact Manager File | |
| .bcmx | Configuration Files | Business Contact Manager Customization | |
| .bcp | Development Files | Borland C++ Makefile | |
| .bct | Data Files | Adobe Bridge Thumbnail Cache File | |
| .bdc | Data Files | Babylon Dictionary File | |
| .bdd | Audio Files | CARA Sound Radiation Data File | |
| .bdf | Font Files | Glyph Bitmap Distribution Format | |
| .bdic | Data Files | Chrome Dictionary File | |
| .bdp | Microsoft Files | Exchange Diagnostic Message | |
| .bdr | Microsoft Files | Exchange Non-Delivery Report Body File | |
| .bdr | Partially Downloaded Files | Publisher Borders File | |
| .bean | Text Files | Bean Rich Text Document | |
| .bf | Game Files | CryoBF Game Data File | |
| .bf2 | Development Files | Bidfax 2000 Java SE Platform Integration File | |
| .bfg | Game Files | Big Fish Games Application File | |
| .bfx | Data Files | Bitware Fax Document | |
| .bgl | Game Files | Flight Simulator Scenery File | |
| .bgt | Data Files | Graphics Accounts Data File | |
| .bi | Text Files | Binary Byte Sequence File | |
| .bib | Text Files | BibTeX Bibliography Database | |
| .bidule | Audio Files | Bidule Layout File | |
| .bif | Binary Information Files | BioWare Infinity Engine File | |
| .big | Game Files | Electronic Arts Game Data File | |
| .bik | Digital Video Files | Bink Video File | |
| .bim | Data Files | Bytessence InstallMaker Document | |
| .bin | Binary Image Files | Binary Disc Image | |
| .bin | Vector Graphics Files | Nero Burning ROM Disk Image File | |
| .biq | Game Files | Civilization 3 Scenario File | |
| .bk | Backup Files | FrameMaker Book File | |
| .bkk | eBook Files | BookBuddi eBook File | |
| .bkn | Backup Files | WordPerfect Automatic Backup File | |
| .bkp | Backup Files | Backup File | |
| .bkup | Backup Files | Backup File | |
| .bkw | Font Files | FONTEDIT Mirror Image Font Files | |
| .blb | Archive Files | Blob Data File | |
| .bld | Data Files | Envisioneer Building Project File | |
| .blend | 3D Graphics Files | Blender 3D Data File | |
| .blend1 | Backup Files | Blender Document Backup File | |
| .blf | Registry Files | CLFS Base Log File | |
| .blg | Data Files | Windows Binary Performance Log File | |
| .bln | Data Files | Golden Software Blanking File | |
| .bm2 | Raster Graphics Files | Subspace Bitmap File | |
| .bmp | Raster Graphics Files | Bitmap Image File | |
| .bmt | Vector Graphics Files | Ami Pro Button Image File | |
| .bmz | Compressed Files | Portal Bonus Map Zip File | |
| .bna | Text Files | Barna Word Processor Document | |
| .bna | Map Files | Atlas Terrain Map File | |
| .bnk | Bank Files | Test Drive Unlimited Data Package | |
| .bnp | Digital Video Files | Sony Camcorder Video Data File | |
| .boc | Text Files | EasyWord Big Document | |
| .bok | Data Files | TestGen Testbank File | |
| .book | Page Layout Files | FrameMaker Book File | |
| .box | Data Files | E-mail Mailbox | |
| .bpdx | Multiple Use Files | Acrobat Batch PDX File | |
| .bpf | Page Layout Files | Baan ERP Document | |
| .bpl | Multiple Use Files | AutoCAD Batch Plot File | |
| .brain | Data Files | PersonalBrain Mind Map File | |
| .brd | Data Files | EAGLE Circuit Board File | |
| .brsar | Audio Files | Wii BRSAR Audio Package | |
| .brstm | Audio Files | BRSTM Audio Stream File | |
| .brw | Data Files | Calyx Point Borrower File | |
| .bss | Raster Graphics Files | Resident Evil Background Images File | |
| .btd | Document Files | Business-in-a-Box Document | |
| .btf | Data Files | NationsBank Check Images | |
| .btif | Data Files | NationsBank Check Image File | |
| .btinstall | Data Files | uTorrent Installer File | |
| .btm | Data Files | BizTalk Map File | |
| .btm | Executable Files | 4DOS Batch File | |
| .btn | Development Files | AutoPlay Media Studio Button File | |
| .btr | Database Files | Btrieve Database File | |
| .btw | Page Layout Files | BarTender Label | |
| .bun | Audio Files | Cakewalk Bundle File | |
| .bup | Backup Files | DVD IFO Backup File | |
| .bvp | Data Files | VodaHost BlueVoda Project File | |
| .bwf | Audio Files | Broadcast Wave File | |
| .bwt | Control Files | BlindWrite 4 Disk Image | |
| .bww | Audio Files | Bagpipe Player File | |
| .bxx | Configuration Files | BS Contact Parameter File | |
| .bz2 | Compressed Files | Bzip2 Compressed File | |
| .bzabw | Text Files | Compressed AbiWord Document | |
| .bzip | Compressed Files | Bzip Compressed Archive |