What is a canceled stamp?

A canceled stamp is a stamp that has been postmarked, which is a marking, made on the stamp to indicate the date and time that the item was delivered into the care of the postal service. This can be on a letter, package, postcard or the like. Modern postmarks are often applied simultaneously with the cancellation or killer that marks the postage stamp(s) as having been used. Postmarks may be applied by hand or by machines, using methods such as rollers or inkjets, while digital postmarks are a recent Innovation.