whats a quality backlink?

is it a link in content that is related to your site/page

is backlinks from blogs good quality


whats is a good quality backlink??

A backlink is weighed on a ton of different metrics. A few of which being:

PR of domain
PR of page
Niche relevancy
Less than 5 OBLs on the page
No REL= attribute (dewfollow)
Anchor Text (targeted vs untargeted)
Inbound links to the page

Etc. A link isn't inherently good or bad just because it's from a "blog".