A market in which prices are high or rising, or. This is basically a line of credit at a brokerage firm. Clearly, when you buy on margin you hope that your stocks will rise. Medium sized companies. Brokers with a seat on the exchange gather to bid on stocks.
Options are basically bets.
This gives you the right to sell 100 shares near the current price. This gives you the right to buy it near the current price. When institutional investors do it on a grand scale, it's called program trading. Only after you've moved beyond basic investing, and even then proceed with caution. Options really run counter to a long term investment plan.