Brightness: Expressed in 'candelas per square metre' (cd/m²) or 'nits', this specification measures the greatest amount of light that comes from a screen displaying pure white. Nearly all LCDs have a brightness level of 250cd/m² or greater, which should be more than sufficient. (In comparison, CRT monitors typically average about 100 cd/m² - though you might see some high-brightness CRTs.) Vendors usually set the brightness level to maximum on new monitors to impress customers. High brightness can be eye-catching for video and graphics, but it can be uncomfortable over time, particularly for text viewing - and it may cause certain photographic nuances to wash out. After using the monitor for a while, you will likely want to turn the brightness down a bit to spare your eyes. Many monitors offer screen modes that change the brightness (and sometimes colour and other characteristics) to make certain types of content look best.
Digital versus analogue: If you have a graphics card with digital video-out - and if your computer is less than three years old, you probably do - choose an LCD that has DVI (Digital Video Interface) input. The image won't have to convert from analogue to digital and back again, so it will be clearer. Even if you don't have a DVI port on your system, choosing a digital LCD makes sense, because your next desktop PC will have a DVI port - and most digital-capable monitors also have the traditional analogue VGA (Video Graphics Array) connection. Digital inputs are almost ubiquitous now. Only low-end models tend to have only an analogue port. Very few notebook PCs come with digital outputs for external monitors. However, some notebooks can gain a DVI connection when they attach to a docking station or port replicator. Note that there are two types of DVI connections found on typical LCD monitors: DVI-D and DVI-I. DVI-D is a digital-only port; DVD-I can accept either an analogue or a digital input. You'll need a special connector to hook up to your PC's VGA analogue port, however. DVI-I obviously provides greater flexibility.
Special inputs: As users do more video and photo editing at their PCs - and as more watch DVDs on them - more monitors offer inputs we used to see only on TVs or peripherals. Videographers or DVD aficionados may want to keep their eyes peeled for component, S-Video or composite input ports.