Universal fabric care symbols are used to reduce language on yarn and clothing labels.  These symbols indicate how best to care for an item that will be made with a particular fiber.  You might consider, when giving a hand crafted item as a gift, including the yarn label with the care information so that the recipient will know how to care for the item.

There are five basic categories of care symbols:

Washing: a trapezoid-shaped tub filled with water.
Dots indicate water temperature when washing.