Annual contributions to an IRA are tax-deductible, but upon retirement, withdrawals are taxed as regular income. Many online brokerages offer IRAs in addition to regular non-IRA accounts. IRAs may invest in many of the same securities available to regular investment accounts. A request to buy or sell securities at a determined price. Limit orders allow you to define the highest price you're willing to pay when buying, or the lowest price you're willing to accept when selling.
Most online investors use limit orders routinely, and certainly when trading volatile securities.
Margin loans are paid back, plus interest, when the stock is sold. In many cases, margined positions must be backed up by collateral, usually a certain level of cash in the brokerage account. Market capitalization is the total value of a company, measured as share price multiplied by the total number of shares outstanding. Market cap is an important indicator of a company's buying power, since most mergers and acquisitions are often accomplished with stock, not cash. Also known as a specialist.