Inkjet printer operate by propelling variably-sized droplets of liquid or molten material (ink) onto almost any medium. They are the most common type of computer printer for the general consumer due to their low cost printing, high quality of output, capability of printing in vivid color, and ease of use.

Like most modern technologies, the present-day inkjet printer has built on the progress made by many earlier versions. Among many contributors, Epson, Hewlett-Packard and Canon can claim a substantial share of the credit for the development of the modern inkjet. In the worldwide consumer market, four manufacturers account for the majority of inkjet printer sales: Canon, Hewlett-Packard, Epson, and Lexmark.

The emerging ink jet material deposition market also uses ink jet technologies, typically piezoelectric jets, to deposit materials directly on substrates. The idea is that because the head need not be replaced every time the ink runs out, consumable costs can be made lower and the head itself can be more precise than a cheap disposable one, typically requiring no calibration. On the other hand, if the head is damaged, it is usually necessary to replace the entire printer. Epson has traditionally used fixed print heads featuring micropiezo technology.

Inkjet advantages
Compared to earlier consumer-oriented colour printers, inkjets have a number of advantages. They are quieter in operation than impact dot matrix or daisywheel printers. They can print finer, smoother details through higher printhead resolution, and many consumer inkjets with photographic-quality printing are widely available. Many small office activities choose this type for any reasons: low price and easy operating.

In comparison to more expensive technologies like thermal wax, dye sublimations, and laser printers, inkjets have the advantage of practically no warm up time and lower cost per page (except when compared to laser printers).

For some inkjet printers, monochrome ink sets are available either from the printer manufacturer or third-party suppliers. These allow the inkjet printer to compete with the silver-based photographic papers traditionally used in black-and-white photography, and provide the same range of tones – neutral, "warm" or "cold". When switching between full-color and monochrome ink sets, it is necessary to flush out the old ink from the print head with a special cleaning cartridge.

As opposed to most other types of printers, inkjet cartridges can be refilled. Most cartridges can be easily refilled by drilling a hole in and filling the tank portion of the cartridge. This method is more cost effective for asmall office activities as opposed to buying a new cartridge each time one runs dry.

Inkjet disadvantages
Inkjet printers may have a number of disadvantages:

The ink is often very expensive. (For a typical OEM cartridge priced at $15, containing 5 mL of ink, the ink effectively costs $3000 per liter--or $8000 per gallon.) According to the BBC (2003), "The cost of ink has been the subject of an Office of Fair Trading investigation.

Many "intelligent" ink cartridges contain a microchip that communicates the estimated ink level to the printer; this may cause the printer to display an error message, or incorrectly inform the user that the ink cartridge is empty. In some cases, these messages can be ignored, but some inkjet printers will refuse to print with a cartridge that declares itself empty, in order to prevent consumers from refilling cartridges. Thus, Epson embeds a chip which prevents from printing when the chip claims the cartridge is empty, although a researcher who over-rode the system found that in one case he could print up to 38% more good quality pages, even though the chip stated that the cartridge was empty.

The lifetime of inkjet prints produced by inkjets using aqueous inks is limited; they will eventually fade and the color balance may change. On the other hand, prints produced from solvent-based inkjets may last several years before fading, even in direct sunlight, and so-called "archival inks" have been produced for use in aqueous-based machines which offer extended life.

Because the ink used in most consumer inkjets is water-soluble, care must be taken with inkjet-printed documents to avoid even the smallest drop of water, which can cause severe "blurring" or "running." Similarly, water-based highlighter markers can blur inkjet-printed documents.

The very narrow inkjet nozzles are prone to clogging with dried ink. The ink consumed cleaning them - either during cleaning invoked by the user, or in many cases, performed automatically by the printer on a routine schedule - can account for a significant proportion of the total ink installed in the machine.

Third-party ink suppliers sell ink cartridges at significantly reduced costs (often 10%−30% of OEM cartridge prices) and also sell kits to refill cartridges, and bulk ink, at even lower prices.

Many vendors' "intelligent" ink cartridges have been reverse-engineered. It is now possible to buy inexpensive devices to reliably reset such cartridges to report themselves as full, so that they may be refilled many times.