Buy side firms and Sell side firms

I have been reading about financial markets for a while, and often encountered this terminology of "buy-side and sell-side firms". Earlier, I was too lazy to know what it really meant and just overlooked it, since it never became a road block to my overall understanding of the actual topic i would be reading :-P Anyways, here it is, finally! (directly lifted from Wiki Answers)

On Wall Street, "buy side" refers to firms that invest money or 'buy' securities and "sell side" refers to the investment banks that provide the buy side firms with products and services such as initial public offerings (IPO's), secondary offerings, trading, research, conferences, etc. The "sell side" firms are 'selling' IPO's and services to the buy side firms.
Examples of buy side firms would be large mutual fund companies like Fidelity or T Rowe Price. Examples of sell side firms would be investment banks like Goldman Sachs, Morgan Stanley, etc.
Most of the large investment banks also have small buy side operations that are run separately from the larger sell side. For example, you can buy a mutual fund from Morgan Stanley or Merrill Lynch, but this isn't where these firms make most of their money.