“firmware” to the average PC user and you'll likely elicit a blank stare in return. But the concept isn't really that hard to understand, and once you have this knowledge, you can quickly improve your PC and any number of other devices, making them faster, more stable, and supplemented with features that didn’t come in the box.

Firmware is a set of permanent instructions on a piece of hardware, stored in the device’s read-only memory. It’s analogous to a driver file that’s embedded in the device, providing the hardware identical information each time it powers up. While you can modify the hardware’s interaction with your operating system via software drivers, certain lower-level functions of a device remain constant and unchangeable. That’s firmware.

But even though we call it "unchangeable," it isn't necessarily so. Some firmware, located in the device’s PROM or EPROM (programmable read-only memory or erasable programmable read-only memory), can be altered, or "flashed." You do this by running software applications from the device’s manufacturer; such programs load new firmware onto the device to extend its feature set, life span, or performance, as well as to correct significant errors.

Firmware isn't a PC-only concept. You can (and should) update the firmware in external devices such as network-attached and external storage hubs, as well as wireless routers and portable media players. You can even upgrade the firmware on your phone, depending on the model. (That's how people hack the iPhone--and how Apple tries to outsmart them. Firmware updates from Apple overwrite the customized firmware that some people use to jailbreak and unlock the devices, sending hackers back to the drawing board to search for a new, deployable approach.) Other products in your house--like Microsoft’s Xbox 360, which gained features such as native 1080p HD support and a new user interface via a single download--can also benefit from firmware updates.

The frequency of a device’s firmware updates varies by manufacturer and product. Though you shouldn’t expect to find updates on a weekly basis, you should perform a firmware search for all of your PC’s devices at least once per quarter. Manufacturers often stress that you should ignore firmware updates unless you’re having a problem with your hardware; but we recommend that you run your hardware on the most up-to-date firmware you can find, since the increased stability (as well as the potential to gain new features) is worth it.

Unless you're an expert, you probably don't want to use third-party firmware like the iPhone hacks mentioned above. Such offerings are typically more complicated to install--and more likely to cause problems--than are normal, manufacturer-supplied firmware updates. They can also void a warranty. Unless you know what you're doing and you don't mind the risks, stick to official firmware.