What is a .inf file?

About the format

An .inf file is a setup-information script — plain text in an INI-like syntax that tells Windows how to install something, most importantly DRIVERS: which files go where, which registry values to set, which device hardware IDs the driver matches. Driver packages are .inf + .sys + .cat (the signature catalogue), and 'installing a driver manually' concretely means right-clicking the .inf → Install, or pointing Device Manager's update-driver dialog at the folder containing it. Windows validates the package's signature against the .cat file, which is why editing an .inf usually breaks installation on modern 64-bit systems. The format's dark history is autorun.inf — the file that made USB sticks auto-execute malware on insertion, a behaviour Microsoft killed for removable drives back in 2011; a stray autorun.inf on a USB stick today is either harmless legacy or a hint that the stick met an infected machine at some point. Reading an .inf is safe and sometimes genuinely useful for seeing exactly what a driver will install.

How to open a .inf file

Is a .inf file dangerous?

The file is text, but installing a driver package is a system-level trust decision — vendor sources only.

Related file types