| Extension |
File Type |
File Description |
| .y | Compressed | Amiga Yabba Compressed File |
| .y | Raster Image | Subsampled Raw YUV Image |
| .y | Developer | Yacc Source File |
| .y3a | Game | Yu-Gi-Oh! ONLINE 3 Avatar File |
| .y3d | Game | Yu-Gi-Oh! ONLINE 3 Deck File |
| .yab | Developer | Yabasic Source Code |
| .yal | Vector Image | Arts & Letters Clipart Library |
| .yam | Data | Yahoo! Auctions Data |
| .yaodl | 3D Image | PowerFlip 3D Image File |
| .ybd | Misc | YobiDrive Link File |
| .ybk | Misc | Microsoft Encarta Yearbook File |
| .ybk | Misc | YanCEyWare eBook |
| .ychat | Data | Yahoo! Messenger Chat Log |
| .ycm | Game | Yugioh Card Maker File |
| .ydc | Game | Yu-Gi-Oh! Card Deck File |
| .ydl | 3D Image | PowerFlip YAODL 3D Image File |
| .ydr | Game | Yu-Gi-Oh! Power of Chaos Replay File |
| .ydt | Game | Yu-Gi-Oh! Power of Chaos Data File |
| .yenc | Encoded | yEnc File |
| .yfs | Game | YSFLIGHT Mission File |
| .ygf | Data | Y Graph Format File |
| .ym | Audio | Atari ST Audio File |
| .ymg | Misc | Yahoo! Messenger File |
| .yml | Text | YAML Document |
| .yml2 | Developer | YML Script |
| .ymp | Developer | YaST Metapackage File |
| .ync | Encoded | yEnc Encoded File |
| .ypr | Developer | BYOB Project File |
| .yps | Misc | Yahoo! Messenger Data File |
| .ysp | Raster Image | BYOB Sprite File |
| .yuv | Video | YUV Video File |
| .yuv | Raster Image | YUV Encoded Image File |
| .yz | Compressed | YAC Compressed File |
| .yz1 | Compressed | Yamazaki ZIPPER File |
