What it is:
Ticker tape was the paper strip used to transmit stock prices before the use of computers.
How it works (Example):
The first ticker tape came about around 1867 with the advent of the telegraph. Prices and volumes after every trade appeared from the machine on a long, thin strip of paper, and there was a long delay that got shorter (around 15-20 minutes) as the technology improved by the 1940s and 1950s. Throughout the trading day, new quotes streamed through on the ticker tape.
One of the most interesting effects of ticker tape, aside from the relatively faster information dissemination, was the response of the brokers. To keep a constant eye on stock prices, many brokers who did business on the New York Stock Exchange set up offices near the exchange just so they could get a steady supply of tape from messengers who ran back and forth from the trading floor. Before 2001, stock prices were quoted in fractions (i.e. 20 1/8) instead of decimals (20.125).
Why it Matters:
Whether the name came from the sound the machine made while printing stock prices or from the notion that a movement up or down in price is called a tick, ticker tape is still the colloquial term for a stream of stock prices, including volume. Actual ticker tape gave way long ago to electronic reporting, but today it still stands as symbol of American capitalism (and it's handy for parades, too).