Skim through

What it does: cleansing, emulsifying, foaming, surfactant

Also called: SLES 

The science

SLES is a common cleansing ingredient that's responsible for big bubbles in cleansing products though the foam it creates is a bit airy and loose and not as dense and luxurious as the foam created by SLS. It has excellent emulsification and foamability, making it an excellent cleansing agent.

As for mildness, it goes somewhere in the middle. It’s often confused with sodium lauryl sulfate (SLS), but they are absolutely not the same. The SLES molecule has a bigger water-soluble head part that makes it milder. 

Benefits for your hair

Promotes scalp health

SLES, as a surfactant and cleansing agent, helps to keep the scalp healthy and clean.

TLDR 

SLES is a great, mild ingredient for the hair which acts as a surfactant and emulsifying agent while also creating foam (lather).