There are two most common types of expansion slots in video slots – one is for single-line and the other is for multi-line.
Single-line slots have one row of slots and multi-line slots have multiple rows of slots.
Multi-line slots are generally more popular because they offer more opportunities to win. They also allow players to bet on more lines at the same time, which means they can make more money in a shorter amount of time.
Some casinos also offer bonus rounds that award players when they complete certain tasks such as hitting a certain number of winning spins or making a certain amount of money. Multi-line slots can be very beneficial for players who want to take advantage of these bonus rounds.