Duplex is a possibility to do anything in two ways at the same time. For instance you can send and receive data at simultaneously using one wire or you can speak and listen. Who can do this ? Me not.
OK, for printer Duplexing means ability to prints-on-both-sides. Another words for this: two sided, double-sided, auto duplex, auto duplex unit. Key word here AUTO, and this means that printer can print one both sides fully automatically. Manual duplex means that you will be in position of duplex unit and will assist your printer by flipping pages.
So it is AUTO DUPLEX. Is this cool? Yes, very! Printer will do everything for you, and you really can save paper by printing on both sides without pain.
How it works ? In case if you think that printers print on both sides at the same time, you are mistaken. It will be too hard for them. Instead printer prints one page, flips it and prints second page next. Usually it looks like printer eats page after printing. OK, actually it pulls it back into duplex unit, flips it there and put page back into printing path. It can be separate optional duplex unit or standard part of your printer. One time I though about mechanical hands, which can flip pages. Sounds funny. Actually everything is much simpler.
Is this expensive? Most likely YES and most likely choice of printers with duplexer is limited. HP printers with duplex unit cost much more then regular ones. However Canon PIXMA printers are good exception here. There are a lot of duplex models on the market with quite a good price.
Disadvantages? N0, but you should be ready that in auto duplex mode some features may be limited: Margins can be significantly bigger, only standard paper sizes can be handled correctly.
It is really worth to think about duplex printer if you have to buy new printer.
To be continued…