What is CISS?
CISS means Continuous Ink Supply System and it's a better alternative for color and black&white printing. The system delivers a continuous flow of ink to a special type of ink cartridge, through a capillary system connected to external reservoirs. These external reservoirs can be afterwards refilled with ink when they are almost empty.
How you use the CISS?
So, we have some tanks filled with ink near the printer (external of the printer). We can have 4 or even 8 ink tanks depending of the printer. Trough a system the ink is supplied from the tanks to the ink cartridges inside the printer. It's not so big deal, just that you have instead of the expensive original cartridges some external bigger ones in which you can see how much ink you have left. Usually the original expensive ink cartridges are very often discarded while still containing some ink. I have an Epson Stylus and I know what I am saying :).
Benefits using CISS
When you purchase CISS you get then full of ink (100ml for each color), more than the original cartridges. When the ink is over you only buy the ink and refill the color tank. You can easily see when the the ink is almost over. The CISS tanks contain the equivalent of about 10 to 28 sets of original ink cartridges.
So, if you want to purchase a CISS you can go on the official page here: CISS.For those who have an Epson Printer this link should be handy: CISS Epson.