The OfficeJet Pro L7400 is an all-in-one printer from HP (Hewlett-Packard) designed for both home and small office use. It can print, scan, copy, and fax. The "dot4usb" refers to a specific type of communication protocol used by certain HP printers when connected via USB. The dot4usb is related to the DOT4 (Device Option Technology) port, which is used by some HP printers to enable direct communication with the computer, especially when connected through USB.

The Windows driver for the HP OfficeJet Pro L7400 (dot4usb) is required to ensure the printer functions correctly when connected to a computer running a version of Windows. Without the appropriate driver, your computer may not be able to recognize the printer, or it may not perform all of the printer's functions correctly.