Meet Julian Castro

San Antonio mayor Julian Castro introduces himself and his family ahead of his keynote speech on Tuesday in a video on the Obama campaign YouTube page.

Castro's twin brother, Texas state Rep. Joaquin Castro, will introduce him on stage before he speaks during the 10 p.m. ET hour. Unlike the video, those remarks will mostly focus on contrasting Mitt Romney and President Obama.

"We all understand that freedom isn’t free," Castro will say, according to excerpts published here. "What Romney and Ryan don’t understand is that neither is opportunity. We have to invest in it."