Postage stamps are small pieces of paper that postal authorities affix to letters or parcels. The stamps denote certain specified values that indicate the amount of postage paid. Stamps are commonly used to denote the priority of the letter or parcel being sent. One can purchase postage stamps through coils, booklets, self-service kiosk stamp “sheetlets,” and sheets. There are multiple types of postage stamps. Some such types are listed below for further information:

• Forever stamps
  These stamps are used to send a letter one way at the existing First-Class Mail Letter rate specified by the United States Postal Service (USPS). This rate remains constant even if the sender’s cost of mailing exceeds one dollar. These stamps are valid for non-profit mailings such as magazines. Also, all forever stamps are good for 1 ounce (about 28 grams), regardless of value. These stamps are also commonly classified as first-class, one-ounce “non-denominated” stamps.
• Semipostal stamps
  These regular postage stamps are sold at higher prices than similar, comparable items. Sellers of these stamps earn more money when they sell them. Some profits generated by the sale of these stamps go towards the causes favored by any organization the buyer chooses upon purchasing their semipostal stamps. In that way, these stamps support a noble cause as they encourage buyers to purchase them, and a share of the money spent goes to charitable causes. Many organizations hold semipostal stamps worldwide.

  Generally, semipostal stamps are sold at a price above the first-class rate that the USPS specifies for stamps in general. A good example of semipostal stamps helping charitable causes is the purchase of one by a buyer who wishes to pledge a percentage of their money to a breast cancer research organization.

• Commemorative stamps
  As the name implies, these stamps honor iconic people whose contributions have positively influenced the country. The USPS issues about 140 of these stamps every year. These stamps carry significantly high values due to the image of the icon on them. Also, these stamps may be relatively rare due to their sheer exclusivity. This is why they are highly sought-after in various markets. One may be hard-pressed to find rare stamps with images of icons such as Abraham Lincoln and Martin Luther King.