The Tweet Button is a small widget which allows visitors to share content and connect on Twitter.
Open graph description entity tag
A canonical link element is an HTML element that helps webmasters prevent duplicate content issues by specifying the "canonical", or "preferred".
A scheme.org entity that represents a particular physical business or branch of an organization. Examples of LocalBusiness include a restaurant, a particular branch of a restaurant chain, a branch of a bank, a medical practice, a club, a bowling alley, etc.