A representation of your professional self. You have 1 page to "sell" yourself to a perspective employer. If done right your future employer will feel curious enough to want to talk to you further. To get that interview.
It should accomplish selling yourself as a person who they would want to hire, who has the skills, education, experience they are looking for. Use key power words specific for the company that will catch their attention is as short a manner as possible and give them a good means of contacting you.