Playing at an online casino is increasing in popularity and as there are so many casino games to choose from it can sometimes be difficult to decide which to play which is probably why most people who play online casinos do not stick to one particular game. Casino slots are certainly the most played of all casino games and generally speaking an online casino will have more choice of casino slots than any other casino game but the reason for the popularity of casino slots probably lies in the fact that it is possible to have a big win without placing large bets unlike Blackjack or even Roulette where large bets are required to win big. Casino slots fall into two main categories which are 3 reel slots and 5 reel slots and winning lines can vary from one upwards. Nearly all casino slots at online casinos have jackpots but the really big prizes are at those slots which are designated as progressive jackpot slots and these will always be 5 reel slots. Progressive jackpot slots are usually run by the casino software company and each online casino operator using that software will contribute a certain amount per spin to the jackpot. The fact that the slots jackpot is contributed to by several online casinos means that it builds up much faster and some often reach into the millions of Euro. It should be remembered that if you play progressive jackpot slots you will need to playing for the maximum per line to win the really big money; smaller stakes will result in smaller winnings. Having said that there are usually two decisions to be made when playing casino slots which are the stake per line and the number of winning lines and although to win the massive jackpots you will need to play the maximum per line there is no requirement to also play the maximum number of lines; even playing one line can win the jackpot although obviously your chances are increased the more lines you play.