Total: The total number of impressions seen of any content associated with your page

Organic: The number of people who visited your page, or saw your page or one of its posts in news feed or ticker. These impressions can be fans or non-fans

Viral: The number of times people viewed your page or one of its posts from a story published by a friend

Paid: The number of times people saw a sponsored story or sponsored ad about your page or its posts