Primary and Secondary Markets

Primary Market
An Issuer/Company enters the Primary markets to raise capital. They issues new securities in Exchange for cash from an investor (buyer). If the Issuer is selling securities for the first time, these are referred to as Initial Public Offers (IPO's). Summing up, Primary Market is the means by which companies float shares to the general public in an Initial Public Offering to raise capital.
E.g. If the promoters of a private company, say XYZ makes its shares available to investors, company XYZ is said to have entered the primary market.
Secondary Markets
Once new securities have been sold in the Primary Market, an efficient mechanism must exist for their resale, if investors are to view securities as attractive opportunities. Secondary Market transactions are referred to those transactions where one investor buys shares from another investor at the prevailing market price or at whatever prices both the buyer and seller agree upon. The Secondary Market or the Stock Exchanges are regulated by the regulatory authority. In India, the Secondary and Primary Markets are governed by the Security and Exchange Board of India (SEBI).
For e.g. If one of the investors who had invested in the shares of company XYZ sold it to another at an agreed upon price, a Secondary Market transaction is said to have taken place. Normally investors transact in securities using an intermediary such as a broker who facilitates the process