The term "tea towel" dates back to the 18th century, when "tea towels" referred specifically to special linen cloths which were used to dry teaware.
Teaware (i.e., fine chinaware) was incredibly expensive at the time (though it became cheaper over time as it was imported in massive quantities, and was even used as the ballast for many tea-importing clipper ships that came over from China). For that reason, usually the mistress of the house would be the person to use a tea towel to do the drying. Housemaids were allowed to hem the linen cloth used to dry the dishes, but generally other house servants were strictly not allowed to handle the teaware or tea towels for fear of them damaging these precious items.
Tea towels have been mass-produced since the Industrial Revolution. They may be made from linen, cotton or a blend of materials, but it is important that they be absorbent and, ideally, quick to dry. In recent years, many craftspeople and designers have begun to make smaller runs of unique, trendy or "hipster-esque" tea towels. These can be purchased in many gift shops and independently run boutiques, and on sites such as Etsy. These designs may or may not contain words.
Tea towels are different from tea cloths, which are washcloth-sized cloths used for drying up a tea table and drying tea equipment during a tea ceremony.