The earliest collectibles were included as incentives with other products, such as cigarette cards in packs of cigarettes. Popular items developed a secondary market and sometimes became the subject of "collectible crazes". Eventually many collectible items came to be sold separately, instead of being used as marketing tools to increase the appeal of other products.
To encourage collecting, manufacturers often create an entire series of a given collectible, with each item differentiated in some fashion. Examples include sports cards depicting individual players, or different designs of Beanie Babies. Enthusiasts will often try to assemble a complete set of the available variations.
The early versions of a product, manufactured in smaller quantities before its popularity as a collectible developed, sometimes command exorbitant premiums on the secondary market. Dolls and other toys made during an adult collector's childhood can command such premiums. Unless extremely rare or made as a one-of-a-kind OOAK, in a mature market, collectibles rarely prove to be a spectacular investment.
A collector's item is one which is made without the intention of special interest but due to rarity or uniqueness, a production fault, human error, or other events, becomes sought after due to its rarity in these circumstances. Occasionally, a series of circumstances will take place that result in an item from a collectible series becoming valuable and sometimes sold for substantial amounts of money.