Does the blog/website address we add on various sites like Facebook count as a backlink in the eyes of search engines, especially Google?
Depends on the the site. Most major sites will do
All external links pointing to your site are backlinks (also called inbound links or incoming links).
Several backlinks have a positive effect for SEO and others don't. Backlinks with the
However, even if backlinks from Facebook or Twitter have the
Moreover, communicating about your site with Facebook and Twitter can improve SEO because Google takes into account likes, shares, tweets, etc.