A file extension is the characters after the last dot in a file name. For example, in the file name winmail.dat, the file extension is dat. It helps Windows select the right program to open the file.
Margin is borrowing money from your broker to buy a stock and using your investment as collateral. Investors generally use margin to increase their purchasing power so that they can own more stock without fully paying for it.But margin exposes investors to the potential for higher losses.ut if you bought the stock on margin  paying $25 in cash and borrowing $25 from your broker  you'll earn a 100 percent return on the money you invested. Of course, you'll still owe your firm $25 plus interest.
Market capâor market capitalizationârefers to the total value of all a company's shares of stock. It is calculated by multiplying the price of a stock by its total number of outstanding shares. For example, a company with 20 million shares selling at $50 a share would have a market cap of $1 billion.