Sharing is caring, or so the adage goes. By sharing content you find from within Google+, you provide the people interested in you a wider selection of great content without having to produce it yourself. Think of it as “curation.” Shared content in Google+ behaves similarly to a standard post, but you cannot edit the content that is shared. You can edit only your additions to it.
External websites that have incorporated the +1 button can also publish information to Google+ in the form of a share that includes a reference to the original web-site and a picture and snippet of text taken from the site.