What do you think classifies as sexual assault/harassment?

With all the recent news stories this question HAS to be asked. However, this problem has been around for a few years now
I've noticed girls have been reporting guys for sexual harassment/assault, but than when I read what they actually did, "That is NOT sexual harassment." So what you think classfies as sexual assault harassment. It seems there is no set defenition, so in the US a guy can have his life ruined simply for flirting with a girl, touching her on the arm, or oggling her in the subway.
What do you think classifies as sexual assault/harassment?
Post Opinion