Basic of Stock market is a online trading platform where the buyers are listed in a queue to buy a particular stock and seller are listed in a queue to sell the stock. the listing of Queue is organised by the BEST BUYER and BEST SELLER details to have hassle free order management.
The above is done only thro brokers ONLY. The broker software takes care of the client for order execution, DEMAT account , margin and buy or sell process.
Exchange is responsible of overall settlement and ensure properly closed.
Based on the Trade price gets fluctuated.