For companies that sell products to consumers, a trademark is vital to making their ownership of that material known. Items that contain a trademark are the known property of the entity that owns the trademark.
For example, large companies that sell toys may have each item trademarked. Trademarks prevent others from selling a similar item to make a profit. In fact, no likeliness of that item may be sold to make a profit.
If, for example, a company were to trademark a bear, that bear could not be reproduced in any way and then sold. Trademarks protect the intellectual and actual property of the entity that owns the trademarked product. In addition, the trademark may not be used without the permission of the entity that owns that trademark.