Use tokens to avoid redundant meta data and search engine penalization. For example, a 'keyword' value of "example" will be shown on all content using this configuration, whereas using the [node:field_keywords] automatically inserts the "keywords" values from the current entity (node, term, etc).
Open Graph
The Open Graph meta tags are used to control how Facebook, Pinterest, LinkedIn and other social networking sites interpret the site's content.
The Facebook Sharing Debugger lets you preview how your content will look when it's shared to Facebook and debug any issues with your Open Graph tags.
A one to two sentence description of the content.