Nicolas Bernier

Seamless schema automatically inserts Schema.org and Open Graph metadata inside the page header to improve SEO and social network display. The metadata is extracted by default from the blog content data such as the page title, the post excerpt, the thumbnail image but it can be completed for each blog post, page and attachment using the provided metadata editor for simple properties and even within the page’s HTML code for the more complex ones.
<h3>Configuration</h3>
Configure the default page type and metadata and for the homepage. By clicking Settings / Seamless Schema in the admin page. This is optional since WordPress’ values (page title, description and header image) are used by default. You can also set the Twitter username of your website for the Twitter site cards from here.
If you have Polylang installed, you can set per-language settings.
Authors can fill their Twitter username in their profile for the Twitter site cards.
<h3>How to use</h3>
When editing a blog post, a page or an attachment, you can set its Schema.org content type and metadata. In most cases, the content-type will be Article or Web Page but you can set a more accurate type such as Organization or Product Review.
You can add extra metadata and override the default ones such as the name, description (post excerpt) and image by selecting the property you want in the select box then click the + button. The properties that already have a default value show up in italic in the list. If you set an invalid property for the selected content type, the row will show up in red and won’t be used on the website.
The metadata is added in meta tags in the page header so it’s totally invisible. However, only canonical properties can be added. For more complex types such as home address and product review, you have to add manually the metadata in the HTML code of your post. Have a look at the Schema.org website for more information about the structure.
Additional OpenGraph and Twitter tags can be added in posts, pages and attachments as custom fields prefixed by <code>og_</code> or <code>twitter_</code>. For example, to add the tag <code>og:my_tag</code>, add a custom field named <code>og_og:my_tag</code> with the value you want.

Seamless Schema

Seamlessly insert schema.org and Open Graph microdata into WordPress.

Piyush Mishra

The Open Graph protocol enables any web page to become a rich object in a social graph. For instance, this is used on Facebook to enable any web page to have the same functionality as a Facebook Page.
While many different technologies and schemas exist and could be combined together, there isn’t a single technology which provides enough information to richly represent any web page within the social graph. The Open Graph protocol builds on these existing technologies and gives developers one thing to implement. Developer simplicity is a key goal of the Open Graph protocol which has informed many of the technical design decisions.
<h4>For Developers</h4>
Use <code>add_action('open_graph_head_pre','your_function');</code> and <code>add_action('open_graph_head_post','your_function');</code> to edit the meta data. For an instance of the class.
Always use <code>open_graph_instance()</code> 
Read more on the Plugin URI > <a href="http://www.piyushmishra.com/plugins/open-graph.html" title="Plugin URI" rel="nofollow ugc">Open Graph WP implementation</a> or check out the FAQs

Open Graph WP implementation

Implements the Open Graph Protocol on a WordPress installation. Can be used by other plugins as a dependency.

Seamless Schema vs Open Graph WP implementation