And that purpose is to store a substance (ink or toner powder), which is supplies on demand to the computer with which the cartridge is coupled. Think of a baby (printer) & a mother (cartridge), supplying milk (ink, toner) on demand.
Inkjet (Ink) cartridges vary in size & shape, from the size of a matchbox to a DVD cover.
They can vary in what quantity they contain from 2.5ml for the Canon BCI11BK Black cartridge to 330ml for the Canon BCI1431BK Wide Format cartridge, although the majority are in the 14 to 18 ml range.
The toner printer cartridges normally have greater capacity than the Inkjet cartridges and are more office accentuated while the latter is more often for home usage.
Many offices though do use Ink cartridges, especially smaller businesses.
We thank our sponsers at ABC Printsupplies along with other suppliers for providing this information.