A Device Driver (or simply Driver for short) is a program which controls a specific hardware device on your system. Your OS should already have built into it all the drivers necessary to communicate adequately with devices which were around at or around the time your OS came out. The issue then is why should you update your drivers? Updating a driver may be required due to one or more of the following basic reasons:
1. Your device may be much newer than your operating system.
2. Your device may have features which were not activated in the original set of drivers.
3. Your device may have "bugs" (problems) or incompatibilities which can be reduced or resolved by means of software driver updates.
The truth of the matter is that now that almost everyone has some form of internet connection, manufacturers are willing to rely on regular driver updates to address the above issues. This may mean that a piece of hardware or software may well leave the factory with known issues/incompatibilities or with features which aren't quite working right. The manufacturer then depends on the end user updating their driver over the internet when these issues are finally sorted out and a new driver is released. It's not an ideal situation but that's where it currently stands.
More commonly though, because some games are released with new and sometimes not thoroughly tested features, certain hardware - particularly graphics and sound cards - will require driver updates to properly utilize these features.
As you can see, it is extremely important that you have the latest drivers. Not so much for the sake of "having the latest", but because a great many problems in games and applications are actually resolved in the latest drivers, particularly if the game or application is a popular one.
- Microsoft WHQL Certified and Non-Certified Drivers
Before we go any further, it's important to note that some drivers have been "certified" by the Microsoft Windows Hardware Quality Labs (WHQL) for use with Windows. Other drivers may not have this certification, and you may receive a warning about it in Windows. Without getting into a big anti- or pro-Microsoft debate here, suffice it to say that "non-certified" drivers are safe to use on your machine. WHQL certification is a quality control exercise Microsoft has introduced to ensure driver compatibility with Windows, but it is extremely expensive for developers to get each and every driver they release WHQL-certified, so often drivers are simply not certified. Also WHQL certification does not automatically guarantee that a driver will fix your problems. It simply means it's had an extra level of testing to make sure it doesn't have any major problems in a Windows environment with a range of hardware. The upshot of all of this is that you can safely ignore whether a driver is WHQL certified as long as it's from a reputable company, like those I link to below.
- Beta Drivers
When software is being developed it undergoes various levels of testing, including alpha and beta (pre-release) stages. A beta driver is a driver which is not officially supported by the manufacturer, but often these drivers are "leaked" onto the internet and in recent times can even be downloaded directly from the chipset-makers website (see links below).
While beta drivers can certainly help resolve problems, you should be wary of them due to the fact that they have not been fully tested - and in fact they're often released so that the public can be the guinea pigs at no cost to the developer. As long as you back up data regularly, and if available to you, you use System Restore or some other method to protect yourself, installation of a beta driver is not a giant threat. Just remember that if things do go wrong the drivers are officially unsupported, and in some cases if they're leaked you will not receive much sympathy from technical support.
- Video Card Drivers
Your video card drivers have a large bearing on your graphics performance in games. Certain anomalies in newer games such as flickering or missing textures, objects appears inside another, garbled text, etc. can often be resolved through driver updates. In any case, if you contact a technical support area chances are the first thing they'll ask you is to update your drivers, so do that first and foremost.
There are two types of video card drivers you can download - manufacturer-specific drivers and reference drivers. What's the difference? Well modern graphics cards are based on a reference chipset design by one company which is then used by another company (perhaps with some features added or removed) to manufacture the final video card which sits in your machine. For example, nVidia will produce the GeForce FX reference chipset design, which will then be bought by particular manufacturers such as ASUS who may then decide to use faster memory chips on the final card they produce, or add Video Out capabilities, and so forth.
Because most manufacturers do not currently deviate much (if at all) from the reference design, you can usually download and install the reference driver from the chipset designer's website without any problems. The manufacturer will also have a modified (and usually older) version of these reference drivers which are customized for your exact video card, and will utilize every feature on your card - such as any video out capabilities. For most people I would recommend using the reference drivers as these are the latest and hence have the most recent bug fixes. If you have any problems with the reference drivers (such as inactive features on your card) switch to the manufacturer's latest set.
Below are the links to the driver download pages for the most popular chipset makers:
You can also download a range of official and unofficial (beta, leaked) drivers from the following 3D graphics websites:
Finally, if you want to download manufacturer-modified drivers, the following are some of the more popular video card manufacturers' support sites:
Note you can also download new BIOS for your video card from the manufacturer's website (where available). Generally speaking you shouldn't need to update the BIOS on your video card, but the procedure is much the same as flashing the BIOS on your motherboard - take extreme care.