What is Sell Side?

Legal Definition
Sell side is a term used in the financial services industry.The three main markets the sell side sells these entities on would be the stock, bond, and foreign exchange market.It is a general term that indicates a firm that sells investment services to asset management firms, typically referred to as the buy side, or corporate entities. One important note, the sell side and the buy side work hand in hand and each side could not exist without the other. These services encompass a broad range of activities, including broking/dealing, investment banking, advisory functions, and investment research.
-- Wikipedia
Legal Definition
The methods, processes and tools that are used to sell a product such as catalogues, displays or processing equipment and channels of distribution.