An INF file is the structured text file inside every Windows driver package. It lists supported device identifiers, files to copy, registry settings, services to create and the package's declared version and date.
In practice
Open the folder of an extracted package from a device maker and you will find a file ending in .inf. Its sections name the hardware IDs the package supports and point to the binaries for each architecture. Windows reads exactly these sections when deciding whether the package suits a device.
Common confusion
The INF does not contain the driver's executable code; it describes and installs it. Its date field also does not record when you installed the package. Many packages contain multiple INF files when they serve several related devices.
Why it matters to readers
Because the INF's device list determines matching, it is the authoritative statement of what a package supports. Release notes and product names summarise that list but cannot override it.
A closer look
INF files are organised into named sections that refer to one another, beginning with a Version section and a Manufacturer section that leads to per-model lists. Each model line pairs a description with a hardware ID. The description text is what later appears as the device name in Device Manager, which is why names change when a different package is installed.
