What are assault weapons?

Assault Weapon: To conservatives: There's no such thing. It's just a creation. It's nothing more than a name that Democrats and people on the left created to gin up anti-gun sentiment among people. But there really is no official classification of "assault weapon." It doesn't exist. What gun isn't an assault weapon?

To liberals: A psychological creation to make people think guns are bad so they can gain sympathy and pass laws to get rid of the 2nd Amendment. It's an attempte to gain a renewal of the assault weapons ban, universal background checks and prohibition of high-capacity magazine clips, etc.  It's an attempt to create their Utopian dream world where there are no bad guys and only good guys.