What exactly happens to the skin when it comes in contact with a caustic substance

Obviously the skin is damaged or "burned" but I want to know how this occurs chemically.

I know I'm not being specific in the type of acid involved, (I am not very familiar with chemistry) but in general, what exactly happens during these chemical reactions (or whatever they are) that destroys tissue?

rips to shreads the lipid bylayer of the cells. thus killing them

Caustic substances like NaOH,KOH reacts with proteins of skin and forms a pulp.