Une collection est à la fois un regroupement d'objets correspondant à un thème, et l'activité qui consiste à réunir, entretenir et gérer ce regroupement.
Il peut s'agir d'un loisir : la personne qui constitue et stocke la collection est alors un collectionneur. Ce peut aussi être une profession, celle de conservateur : conservateur de musée (collections d'œuvres d'art, d'objets rares ou anciens), conservateur de bibliothèque ou d'archive (fonds regroupant des documents).
A postage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are printed on special custom-made paper, show a national designation and a denomination (value) on the front, and have a gum adhesive on the back. Postage stamps are purchased from a postal administration or other authorized vendor, and are used to pay for the costs involved in moving mail, as well as other business necessities such as insurance and registration. They are sometimes a source of net profit to the issuing agency, especially when sold to collectors who will not actually use them for postage.
Stamps are usually rectangular, but triangles or other shapes are occasionally used. The stamp is affixed to an envelope or other postal cover (e.g., packet, box, mailing cylinder) the customer wishes to send. The item is then processed by the postal system, where a postmark, sometimes known as a cancellation mark, is usually applied in overlapping manner to stamp and cover. This procedure marks the stamp as used to prevent its reuse. In modern usage, postmarks generally indicate the date and point of origin of the mailing. The mailed item is then delivered to the address the customer has applied to the envelope or parcel.
Postage stamps have facilitated the delivery of mail since the 1840s. Before then, ink and hand-stamps (hence the word 'stamp'), usually made from wood or cork, were often used to frank the mail and confirm the payment of postage. The first adhesive postage stamp, commonly referred to as the Penny Black, was issued in the United Kingdom in 1840. The invention of the stamp was part of an attempt to reform and improve the postal system in the United Kingdom of Great Britain and Ireland, which, in the early 19th century, was in disarray and rife with corruption. There are varying accounts of the inventor or inventors of the stamp.