Primary markets are the markets in which corporations raise new capital. If Microsoft were to sell a new issue of common stock to raise capital, this would be a primary market transaction. The corporation selling the newly created stock receives the proceeds from the sale in a primary market transaction. The initial public offering (IPO) market is a subset of the primary market. Here firms “go public” by offering shares to the public for the first time.
Secondary markets are markets in which existing, already outstanding securities are traded among investors. Thus, if you decided to buy 1,000 shares of RIL stock, the purchase would occur in the secondary market. The National Stock Exchange (NSE) is a secondary market, since it deals in outstanding, as opposed to newly issued stocks.