HDMI and DVI what the difference?

I just don't understand!!!! Can someone explain the difference?

I could be wrong, I think this is correct though>

The are both a digital connection, DVI will transfer Hi-Def picture to your Projector (Hi-Def TV) over a single DVI cable.

HDMI will do the same thing but includes sound. This is the one I'm not sure about.

HDMI is newer.

DVI is video only and HDMI includes audio,too.

HDMI is compatible with DVI.
Yes, sogood51, you are correct.

Have a good evening, everyone!