Stamp dealers put stamps into categories according to their condition. Look at the pictured examples to see the differences among categories. A stamp in mint condition is the same as when purchased from the post office. An unused stamp has no cancel but may not have any gum on the back. Mint stamps are usually worth more than unused stamps. You can begin to judge the condition of a stamp by examining the front of it. Are the colors bright or faded? Is the stamp clean, dirty or stained? Is the stamp torn? Torn stamps are not considered "collectible." Is the stamp design centered on the paper, crooked or off to one side? Are all the perforations intact? Has the stamp been canceled? A stamp with a light cancellation is in better condition than one with heavy marks across it. Now look at the back of the stamp. Is there a thin spot in the paper? If so, it may have been caused by careless removal from an envelope or hinge.