Online slots have a lot of varieties. The most common slots games are:
• Traditional, or 3-reel slots
• Multireel slots (with 5 and more reels)
• Progressive slots (games with progressive jackpots, sometimes the slots machines in the network of casinos are united into 1 chain and all the slots machines in the chain contribute to the progressive jackpot. In this case the sum is the biggest you can win at an online casino).
• Bonus slots or casino slots with bonus games. Different slots can have 1 and more bonus games. Besides, almost all slots have so-called “bonus rounds” which can play for free. In most cases your winning in these bonus rounds is multiplied according to some formula (depends on the game).

Below is the list of the most popular online bonus slots:
1. Goblins slots (have a lot of varieties, but almost all of them have bonus games)
2. Wheel of Wealth slots, similar to the above mentioned slot, don’t have a scatter symbol, but wild symbols and bonus games are present.
3. Most sports-theme-based slots have bonus rounds and bonus games, the most popular ones nowadays are: Soccer Safari Slots, Winter Gold Slots and many others. The slots devoted to winter and summer Olympic games are always on the top of interest when the Olympic games are held and remain popular for several months after the events.
4. Cool Bananas Slots is one of my favorites and US players can enjoy it too.
5. The mentioned above Wheel of Chance has been the undeniable leader for many years by now and remains one of the most-frequently-played games.
6. Cleopatra slot is another popular series of casino slots. It includes traditional games, progressives, bonus games and multireel variants.