What is a Challenge and how does it work?

Challenges give you the chance to see how you stack up against your friends.
On a quiz page, you have the option to 'Challenge your friends'. You can challenge other Sporcle users or enter in emails of people you know. You can also manage your challenges on the Challenges page. You can see your wins and losses, challenge others, check received challenges, and get challenges from the Sporcle Bot.