- A picture (hopefully, but not always from the post)
- The post title
- The blog URL or the post URL
But many people want the post-description to be included too.
There are two things which you need to do to make sure that this happens correctly.
Step 1: Add search descriptions to your blog-posts
If a post does not have a description, Facebook will sometimes try to estimate one based on the contents. But this is not reliable, and it depends on the blog template you have used, and possibly even on other factors, eg at one stage, Facebook just looked for the the first(paragraph) tag with at least 120 characters in it - which gave very odd results for some Blogger users. Alternatively it may try to use your post.summary but this also depends on your template.
A more reliable approach is for you to provide the description-text for each post.
For Blogger, the way to do this is described here.
For Wordpress, you need to to use an SEO plugin like SEO Ultimate to do this.
Step 2: Add Open-Graph tags to your template
Some templates already contain code which causes Facebook to estimate the description correctly. But some don't - and some may use two-step methods, eg relying on schema.org tags to imply Open Graph tags.So, as with descriptions, it's more reliable to ensure you are using the set of tags that Facebook officially supports. These are the Open Graph tags.
You can see how to apply them in Blogger or there are various plug-ins you can use on Wordpress.
Job Done! Once you have made these two changes, when someone shares your blog on Facebook, your own post-description should be shown. Don't forget to test your changes - as described in the Adding Open Graph tags to Blogger article.
What your readers see
Nothing! People who get to your blog using a web-browser, or who subscribe to your RSS feed or who follow-by email don't see anything different after you have done the steps above.The only different is when they share a post from your blog in Facebook: the initial description will come from your Description tag for the the post, not from the overall blog.
What happens for posts that do not have search descriptions
This depends on your blog's template, and on how Facebook is interpreting the information that it provides. You can see what Facebook will do for specific posts using the tag-debugging tool which Facebook provide.Adding descriptions to old posts is tedious. But if your posts are often shared on Facebook, it may be worthwhile for you to allocate some time each day to edit a few posts LINK and update them with a current description. Provided you don't spend too long working out what the description should say, it should be possible to update 200 posts in a three weeks if you spend ten minutes each day doing just this.
What's more, it is possible that adding descriptions to your posts will make them look more attractive in regular Google search results too, which is A Good Thing if search-traffic matters for your blog.
Related Articles:
How to add a Description meta-tag to posts in BloggerHow to apply Facebook's OpenGraph labels in Blogger
Reasons why SEO and search-traffic don't matter for many blogs
