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.
Margin is a loan from your broker to help pay for the securities you buy. Normally, you can finance up to 50 percent of your purchases with margin. For example, if you have $10,000 in cash in your margin account, you can buy $20,000 worth of stock. The shares you buy are collateral for the loan of $10,000.