Why are people so excited about SpaceX?
SpaceX is a space exploration company started by Elon Musk designed to make humanity multi-planetary.  SpaceX is short for Space Exploration Technologies.  The company develops rockets, spacecraft, launch facilities, and satellites to deliver a variety of services to people all around the world.  The long term plan for SpaceX is to create a system of technologies which are capable of bringing humans to Mars and making Mars habitable.