A label is any kind of tag attached with adhesive to something so as to identify the object or its contents. Labels come in many forms and can be differentiated by the type of base material, called stock, that they are printed on, and by the adhesive type that they use.
The most common type is made with a paper stock and a colloquial term for it is a sticker. Labels have many uses, from product identification to name tags.
Stock types
Litho - one of the most common base stocks
Latex - a litho stock with some added latex allows the label to be much more flexible and form around certain curved objects more easily than standard litho.
Various plastics such as acetate, vinyl, and PET film allow a variety of features, such as greater strength, flexibility, transparency, resistance to tearing, etc. They typically require special equipment and printing methods (ultra-violet curing is common) as they do not normally print well with conventional ink. A bumper sticker is usually a vinyl label with a very strong, durable adhesive and Lightfast Inks.
Thermal - direct thermal label stock will change color (usually black) when heated. A heating element in the shape of letters or images can be used to create an image on the label. Custom labels can be easily be made on location in this way. A disadvantage is durability, because another heat source can ruin or obscure the image, or it may fade completely over time
The stock type will affect the types of ink that will print well on them.