Many here need to read more than that. Especially understanding the role of a MM.
How a Market Maker Works
This system of quoting bid and ask prices is good for traders. It allows them to execute trades more or less whenever they want. When you place a market order to sell your 100 shares of XYZ, for example, a market maker will purchase the stock from you, even if it doesn't have a seller lined up. The opposite is true, as well, because any shares the market maker can't immediately sell will help fulfill sell orders that will come in later.
Market makers are required to continually quote prices and volumes at which they are willing to buy and sell. Orders larger than 100 shares could be filled by multiple market makers. This process helps to maintain consistency with markets.
Market Data 
Markets 
AI
