Technically, almost every slot carries a theme in some shape or form. While the theme may not always stand out and be totally obvious, elements of theming will always be there. For instance, on more traditional slot machines, the earliest examples were based on poker, with the symbols represented on the reels being card faces. The later fruit machines also held a theme, with different bubble gum flavors being represented across the symbols and often paying out gum as opposed to cash. The theme is what the slot is about, allowing players to feel different emotions and a greater sense of excitement when playing the games. Slots online have continued these traditions of using specific themes to enhance the games being developed, and these themes come in all shapes and sizes. Regardless of what a player is looking for, a theme is almost certainly going to exist for it.
The theme of a slot dictates not just the symbols that will appear on the different reels when spun, but with online casinos, it's also possible that different characters will be available in the slots games and that greater stories will be told. Some slot games also have bonus rounds that are unlocked when certain symbols appear on winning paylines, allowing players to have a go at something a little bit different while also maximizing their winnings.