Almost all slot machines work the same way, so you can go from slot machine to online slot machine without much noticeable difference.
The things that spin are called reels and they have symbols that stop in random order. They key is to have the symbols stop in a specific combination of patterns so you can receive the largest payout. For any slot game you're playing, you should know if there are any special symbols, rounds, or jackpots. Let's talk a little more about symbols and pay outs and bonuses.
Just a little behind the scenes information about online slot machines is that they are powered by a random number generator (RNG). This generator produces random series, hence the name, of numbers every time you click the spin button. This computer software combined with algorithms is responsible for the symbols that appear on the screen when you spin. This number, symbol, is generated with no clue about the number that came before it. Contrary to popular belief, sitting at one machine all day while have no impact on what symbols will appear next.