| Extension | File Description |
| .IMS | Uncommon Files |
| .IMSP | Uncommon Files |
| .IMT | Data Files |
| .IMU | Uncommon Files |
| .IMV | Uncommon Files |
| .IMW | Uncommon Files |
| .IMX | Uncommon Files |
| .IMY | Misc Files |
| .IMZ | Disk Image Files |
| .IM_ | Uncommon Files |
| .IN | Misc Files |
| .IN$ | Uncommon Files |
| .IN0 | Uncommon Files |
| .IN1 | Uncommon Files |
| .IN2 | Uncommon Files |
| .IN3 | Uncommon Files |
| .IN4 | Uncommon Files |
| .IN5 | Uncommon Files |
| .IN6 | Uncommon Files |
| .IN7 | Uncommon Files |
| .IN8 | Uncommon Files |
| .IN9 | Uncommon Files |
| .INA | Uncommon Files |
| .INB | Uncommon Files |
| .INC | Developer Files |
| .INCA | Misc Files |
| .INCD | Page Layout Files |
| .INCH | Uncommon Files |
| .INCT | Page Layout Files |
| .INCX | Page Layout Files |
| .IND | Page Layout Files |
| .INDD | Page Layout Files |
| .INDENT | Uncommon Files |
| .INDESIGNPL | Plugin Files |
| .INDEX | Uncommon Files |
| .INDIGO | Uncommon Files |
| .INE | Uncommon Files |
| .INF | Settings Files |
| .INF1 | Uncommon Files |
| .INFINI-D | Uncommon Files |
| .INFO | Misc Files |
| .INFO1 | Uncommon Files |
| .INFO2 | Uncommon Files |
| .INFO3 | Uncommon Files |
| .INFO4 | Uncommon Files |
| .ING | Misc Files |
| .INGR | Uncommon Files |
| .INH | Uncommon Files |
| .INI | Settings Files |
| .INIT | Uncommon Files |
| .INJ | Uncommon Files |
| .INK | Raster Image Files |
| .INKBL | Uncommon Files |
| .INKML | Uncommon Files |
| .INL | Developer Files |
| .INLOVE | Uncommon Files |
| .INLX | Uncommon Files |
| .INM | Misc Files |
| .INN | Uncommon Files |
| .INO | Developer Files |
| .INP | Data Files |
| .INPUT | Uncommon Files |
| .INQ | Uncommon Files |
| .INR | Uncommon Files |
| .INRS | Uncommon Files |
| .INS | Audio Files |
| .INSCRIBE | Uncommon Files |
| .INSID | Uncommon Files |
| .INSPECT | Uncommon Files |
| .INST | Uncommon Files |
| .INST2 | Uncommon Files |
| .INSTALL | Uncommon Files |
| .INSTALLER | Uncommon Files |
| .INSTR | Uncommon Files |
| .INSTRUC | Uncommon Files |
| Extension | File Description |
| .INSTRUCT | Uncommon Files |
| .INSURANCE | Uncommon Files |
| .INSURANCE2 | Uncommon Files |
| .INT | Raster Image Files |
| .INTEGER | Uncommon Files |
| .INTER | Uncommon Files |
| .INTEREST | Uncommon Files |
| .INTERIEUR | Uncommon Files |
| .INTERLEAV | Uncommon Files |
| .INTERLOCKF | Uncommon Files |
| .INTERNETMA | Uncommon Files |
| .INTERRUPT | Uncommon Files |
| .INTKEY | Uncommon Files |
| .INTMATH | Uncommon Files |
| .INTO | Uncommon Files |
| .INTREC | Uncommon Files |
| .INTRO | Uncommon Files |
| .INTRODUCT | Uncommon Files |
| .INTRODUCTI | Uncommon Files |
| .INU | Uncommon Files |
| .INV | Game Files |
| .INVADERS | Uncommon Files |
| .INVEN | Uncommon Files |
| .INVENTOR | Uncommon Files |
| .INVENTORY | Uncommon Files |
| .INVERT | Uncommon Files |
| .INV_LOWRES | Uncommon Files |
| .INW | Uncommon Files |
| .INX | Page Layout Files |
| .INY | Uncommon Files |
| .INZ | Uncommon Files |
| .IN_ | Uncommon Files |
| .IN~ | Misc Files |
| .IO | Uncommon Files |
| .IO0 | Uncommon Files |
| .IO1 | Uncommon Files |
| .IO2 | Uncommon Files |
| .IO3 | Uncommon Files |
| .IO4 | Uncommon Files |
| .IO5 | Uncommon Files |
| .IO6 | Uncommon Files |
| .IO7 | Uncommon Files |
| .IO8 | Uncommon Files |
| .IO9 | Uncommon Files |
| .IOA | Uncommon Files |
| .IOB | Uncommon Files |
| .IOC | Uncommon Files |
| .IOCA | Uncommon Files |
| .IOD | Uncommon Files |
| .IOE | Uncommon Files |
| .IOF | Uncommon Files |
| .IOG | Uncommon Files |
| .IOH | Uncommon Files |
| .IOI | Uncommon Files |
| .IOJ | Uncommon Files |
| .IOK | Uncommon Files |
| .IOL | Uncommon Files |
| .IOM | Uncommon Files |
| .ION | System Files |
| .IOO | Uncommon Files |
| .IOP | Uncommon Files |
| .IOQ | Uncommon Files |
| .IOR | Uncommon Files |
| .IOS | Uncommon Files |
| .IOT | Uncommon Files |
| .IOTA | Text Files |
| .IOU | Uncommon Files |
| .IOV | Uncommon Files |
| .IOW | Uncommon Files |
| .IOX | Uncommon Files |
| .IOY | Uncommon Files |
| .IOZ | Uncommon Files |
| .IP | Data Files |
| .IP0 | Uncommon Files |
| .IP1 | Uncommon Files |
