Router manufacturers initially install firmware at the factory. However, this firmware is designed to be freely upgraded by homeowners later as enhancements become available. Updating a router's firmware can increase its performance, security and/or reliability depending on the nature of the enhancements provided. Firmware upgrades generally need to be done infrequently, however.
Firmware exists in read-only memory chips contained inside the router. Firmware does not get erased when a router is powered off nor can it be altered externally by hackers. Homeowners normally only change their firmware when the manufacturer provides a new firmware version on their Web site.
However, router manufacturer Linksys also provides some of its router firmware software code free to programmers on the Internet, offering them the freedom to create their own enhancements. Some of these variations have become popular with technical enthusiasts. Homeowners are normally free to download and install these firmware variants on their routers.