The three reel slots have three vertical sections which combine with the columns to form possible winning combinations which are known as play lines.
Today, these types of slots are also called classic slots. Since they have just three vertical sections, they limit the possible number of winnings of a player.
However, this limitation is not spread out to the amount of winning that a player is likely to get. They also called reel slots, will be the 3-reel slots.
The three slot machines do not pay as often as other types of slots with more reels, however, when the winning happens, the payout is always high.