Balancers in Factorio are mainly used to distribute items on multiple belts or belt lanes in a balanced manner.
We strongly advise here at Stealth for players to have one, as it definitely helps you to save resources and items, while making sure that you're using just the right amount of them.
There are also ways to help you in creating your very own balancer in Factorio.
With that, here's a guide on everything you need to know about balancers in Factorio, including the blueprint, compendium of designs, and more.
Balancer guide: blueprint and compendium of designs
There could be two possible types of belt balancers; namely the throughput and universal balancers. The first one can give you access to a system of passing through items in either limited or unlimited state.
Throughput balancers can be classified as a throughput limited and a throughput unlimited balancer. Throughput 'limited balancers' may not be able to give their maximum output, while the throughput 'unlimited balancers' could do so.
The universal balancers on the other hand can balance evenly between any amount of inputs and outputs. It has a built-in back looping function that is not present with the throughput balancers.
For a compendium of balancer blueprints, click here.
There's also another aspect called a 'lane balancer'.
Lane balancers can be classified as output balanced or input balanced.
According to the official Wiki page of Factorio, the 'input balanced lane balancers' can draw evenly from each side of the input belt. While the output balance lane balancers can also draw evenly, but on the lanes of the output belt.