HP's inkjet printers cover a wide spectrum. They have photo printers in various sizes, business printers, value models for home use and a number of specialized models for various applications.

In any given category, HP tends to be one of if not the best print quality when compared to the competition. A big part of the reason for this is the technology they put into their cartridges.

Most HP ink cartridges include not only the ink but also the printhead. The printhead is the component in a printer that actually sprays the ink onto the paper. In most other brands of printers, the printhead is part of the printer itself rather than the cartridge.

Over a period of time, as the printer gets used more and more, this printhead can start to deteriorate and the quality of printing can suffer because of it. Eventually this printhead will wear out and need to be replaced. In most cases, replacing the head costs as much or more as buying a whole new printer so at this point the printer often gets thrown out and replaced.

By putting the printhead on the cartridge itself, HP avoids this problem of the head wearing out. Over the course of months or years, the print quality will stay pretty much the same as it was when the printer was brand new because each time the ink is replaced, so is the printhead.

There are a couple of drawbacks to this system, however. The first is that the cartridges tend to be a little more expensive than some of the competition's. Each time you replace the ink you'll have to pay a little more, but this added cost will even out when you consider you would eventually have to pay to repair or replace most other brands.

The other disadvantage to HP's system is that their cartridges tend not to work very well when refilled. Because the head is part of the cartridge and is not designed to last beyond the expected life of the ink, it can wear out if the empty cartridge is reused.

You're usually safe with a single refill but after refilling it once, it's hit or miss as to whether you'll run into problems.