A buyer is any person who contracts to acquire an asset in return for some form of consideration.
When someone gets characterised by their role as buyer of certain assets, the term "buyer" gets new meaning:
A "buyer" or merchandiser is a person who purchases finished goods, typically for resale, for a firm, government, or organization. (A person who purchases material used to make goods is sometimes called a purchasing agent.)
In product management, buyer is the entity that decides to obtain the product.
A buyer's primary responsibility is obtaining the highest quality goods at the lowest cost. This usually requires research, writing requests for bids, proposals or quotes, and evaluation information received.