Google+ Sign-In button allows users to authenticate on websites using their Google+ account.
Use your Facebook account to sign into other sites and see what your friends are doing across the web.
Google+ platform websites integration using the Google+ platform tag.
The Tweet Button is a small widget which allows visitors to share content and connect on Twitter.
Let visitors recommend your content on Google Search and share it on Google+.
Facebook's Like button is the quickest way for people to share content with their friends. A single click on the Like button will 'like' pieces of content on the web and share them on Facebook. You can also display a Share button next to the Like button to let people add a personal message and customize who they share with.
Apps that link to your content can then use this metadata to deep-link into your app, take users to an app store to download the app, or take them directly to the web to view the content.
Open graph description entity tag
Chrome for Android, since version 39 supports the "theme-color" meta tag to allow websites control the background color of the tab's UI header.