Who is Mohammed Emwazi aka “Jihadi John”?

Today, a British national named Mohammed Emwazi was identified as “Jihadi John,” the ISIS fighter who beheaded hostages in videos posted on YouTube. We’re learning more about Emwazi, who was born in Kuwait but grew up in England in a well-to-do family. What do we know about him and his journey from computer programmer to jihadist in Syria?