is a type of aftermarket firmware
for wireless broadband routers
. Available online as a free download, DD-WRT contains special features and optimizations designed to improve on the standard firmware that router manufacturers provide with their products.
Routers do not require DD-WRT firmware for standard operation. However, many networking enthusiasts install it in place of the manufacturer's firmware with the goal of extracting better performance or capability from their routers. For example, DD-WRT provides functionality that other types of firmware may lack such as
Originally designed for use with certain models of Linksys routers, DD-WRT has expanded over the years to be compatible with other popular brands.
More - DD-WRT Home Page