It's common knowledge to everyone that acids, at least the lowest PH ones, are corrosive, as can be seen with HCL. People tend to know a lot about what acids do to the body.

But here is my question:

What do alkalis do?

Of course they neutralise acids, but I don't know what they do on their own, what they do to the human body, if they are dangerous at high PH levels etc... I think it's a wasp sting that is alkali? Or maybe a bee sting?
I've gone through secondary education answering chemistry questions on acids and alkalis, and gotten A's, but I have never actually known what they do on their own.
Can someone give me some info?