Does implantation bleeding really happen? if so, can you describe what it looks like and how soon it could happen?

Not really, but...: My answer is no, but it appears in many medical textbooks! the problem is the term has no exact definition: it's a throw-away term to describe bleeding in or around the developing embryo in 1st trimester of pregnancy. What women online seem to "think" - or want - it means is bleeding exactly at the time of implantation, which is around 7 days after fertilization: this is absolute nonsense.