If you own a printer, from time to time you'll run out of ink.
Instead of throwing the cartridge out, see if there are any services in your area for toner cartridge recycling - services are available in most areas nowadays.
Recycling toner cartridges isn't something you do every day, but it's important!
By recycling, you'll probably save yourself some money on your new toner cartridge, you'll avoid adding a heap of concentrated toxins into landfill, and you'll avoid the emissions and waste by-products required for manufacturing a new cartridge.
Many printer retailers will offer their own scheme of discounts to people with old cartridges, then they'll get the printer cartridges remanufactured.
Some companies will offer a straight buy-back scheme - where you can drop your used toner cartridge into the shop and they'll give you cash.
If your retailer or manufacturer doesn't have a toner cartridge recycling scheme, you can still recycle through other-brand or generic local printer shops. They'll often accept most brands of cartridge, clean them up and refill the ink, then on-sell them.
Because it saves you money, recycling toner cartridges is generally a no-brainer.
There is a cost however. You'll need to spend a little more upfront to buy a high yield toner cartridge - one that is going to survive being refilled and cleaned over and again.
Cheap toner is available, so forking out a little more to begin with is a decision that requires weighing up the short term cost with long term monetary and environmental benefits.