The hero ingredients in heat protectants that stash your hair from a bad hair day are silicones.
According to All Things Hair, the specific silicones in heat protectants are cyclomethicone and dimethicone.
The silicone coating is also water-resistant and is in many ways like a primer for your hair.

Heat protectants decrease the porosity of your hair.
They also help heat tools grip your hair better.
Who would benefit from a heat protectant?

Heat protectants benefit everyone, but especially aid people with damaged hair, perAll Things Hair.
Leonor Greyl Detangling Milk Styling Spray is a creamy, coconut-infused heat protectant that works wonders for dry hair.
At best, heat protectants will only abate heat damage by 50% (per Hairstory).

Another great protectant that offers UV protection is Living Proof Restore Instant Protection Spray (perByrdie).
It works on wet or dry hair, which makes it great for styling touch-ups.
confirm to use tools with adjustable temperature tweaks and to not use a higher temperature setting than necessary.
And this is something that not even heat protectant can save you from.