Impact printers are really becoming antiques; you don't see them around much. They are called this because they work like an old typewriter (with a little ball or keys with letters) that strike a ribbon and transfer a piece of paper. Or another style is called a "dot matrix", because little pins would tap out a lot of little dots in a grid to make letters and shapes. The only reason they still exist, is because they can still fill out older style forms with carbon or create brail transcripts; since they actually strike something to the paper with some force. But now days these are becoming very rare other than at old bureaucracies.
Laser printers work by shooting a laser at a rotating drum. Where the laser hits the drum, it magnetizes it, and the drum passes over some microscopic ink-dust; which gets picked up in the magnetized areas. As the drum keeps rotating a piece of paper is passed by, and underneath is an even stronger magnetic attraction, which causes the dust to jump from the drum to the paper. The paper passes by a hot "fuser" which basically melts or bonds the ink-dust into the paper.
Ink Jet Printers
Ink Jet printers work by having little nozzles squirt ink at a page, as this head (which holds a bunch of nozzles), passes back and forth across the page. These little nozzles literally "jet" the ink, and that's where the name comes from. An older variant actually called the ink shot at the page "bubbles", and so the printers were called bubble-jets; but it is the same basic thing.
There are a few other "rarer" technologies; like some thermal transfer or wax/die sublimation printers for higher end photographic work. They work sort of like little iron-on transfer T-Shirt decals; literally heating on some colors to a page. But they tend to be for specialty jobs, like making photos.
Which is best?
Now laser and ink-jet printers each have different advantages and disadvantages, that can help you decide which you want to buy.
- The advantage to laser printers is that they can be very fast (do many pages quickly), and they use a dry toner (ink-dust). Once the ink is fused to the paper, it doesn't fade or rub off. Toner is usually cheaper for how many copies you get out of it; but more expensive overall, just you replace it much less often.
- The disadvantage is that most of them are black and white, and they tend to be bigger and more expensive. There are some color laser printers, but they tend to be even more expensive, and so most individuals don't buy them yet; being more for businesses.
- Ink-jet printers tend to be less expensive to buy the printer, and they almost all do color.
- But the ink tends to run out more often and require more refills than laser printers. And because the ink just squirted on to paper, rather than fused in so it can fade over time and if you don't wait for it to dry, or you drip water on it, then it can smear. Also since ink-jets literally squirt ink on the paper, the paper can absorb the ink and you can get bleeding effects, or dramatically different results depending on the quality of paper. Whereas toner based laser printers tend to look better on cheaper paper.
In general, if you're doing fewer pages and in the home, and you want to be able to do color and don't mind lower volume; then ink-jet printers are great. But if you tend to be working on a book, transcripts or do more high volume printing; then laser printers can be much better values.
- Pages per Minute; which is just that, how fast the printer can print a page, or more accurately, how many pages it can do in each minute. People don't realize how long a minute is when they are waiting for the printer to finish; especially when they just printed a lot of pages.
- DPI; for "dots per inch". The idea is the more dots per inch, the better (smoother) each letter will look, especially in smaller sized characters. So generally more is better. However, there are some things to know; like different technologies compare different. Ink-jets squirt ink on a page, but the page absorbs that ink and it can bleed or splatter. Toner based printers (laser) tend to fuse dry-ink dust on a page, so are crisper and doesn't bleed. So a laser and ink-jet printer with the same DPI are not necessarily the same quality; in most cases the laser printer will look better. Only on high quality (expensive) paper will the ink-jet come close to the laser in quality. As an over-generalization, I just divide the ink-jets resolution by two when comparing them to laser printers.
Which brings us to the question; how much resolution do you need? Well, it matters what you are doing. For most black text at normal sizes, 300 x 300 looks pretty good and 600 x 600 is nice and sharp. If I'm doing lots of gray-tones, logos, small text, or doing page/image reductions, then 1200 x 1200 is better still. Even at these resolutions, it is getting into the quality of the paper making a noticeable difference; with shiny, high gloss and tight weave papers allowing for better results.
With color photographs and images, quality can matter even more. A lot of it will have to do with the resolution you take the picture, and again the quality of the paper, but as a generalization, more is better. Almost all printers now days have different techniques for getting more or better looking color. So if you care a lot, it helps to read product reviews; but if you are the average user, most printers can look pretty good if you use them correctly.
English writing is vertically oriented and has lots of vertical lines in it; so it needs fewer dots vertically than horizontally. Some printers take advantage of that and are asymmetrical, and have something like 1200 x 600 DPI. This makes sense if you print your pages normal mode (up and down) and if you use mostly English; but if you print them sideways (landscape) or do lots of drawings or photos, then you may be sacrificing resolution (quality) in directions that matter. Your usage will make an impact on the quality and what resolution is good enough for you.
Some printers have an option called "duplexing"; being able to print on both sides of a page. I find this very handy at saving paper on larger documents. This option is not cheap, or common, but for some uses it is worth the price. Because of the price, it is more used in businesses than homes.
Printers have to be connected to your computer... and usually wireless (WiFi) is the best way to go.
So you should now understand a lot more about printers and their terms than you did a few minutes ago. If not, what can I say? Sometimes free advice is overpriced.