In your opinion what is shame?

I already have an idea of what it is in my own opinion, but i wanted some more opinions before i write this paper. So in your opinion what is shame? and what might cause it these days? Back in the day having sex with another man/women other than your husband or cheating on your significant other brought across shame, like in the puritan village in the scarlet letter, she felt shame, but now a days that type of stuff doesn't really bring shame to people. So what do you think shame is?