Stock market is the place where we can buy and sell the stocks. It all depends up on the buyer and seller it is purely based on the demand and supply process.
We have many exchanges where we have to stand with broker in order to buy and sell the stocks.
IPO is the process where we can buy and become owner of the share all the shares are equally divided.There is no way in order to buy our invested money or to claim dividend the only way is to buy and sell the share based on the demand and supply.
There are various patterns in order to invest and disinvest the shares.