Yep. Some webmasters have a lot of these kinds of links and others have one way links without reciprocating.
Ah thanks guys If I host two sites (Example toys.net and biblesales.org) and there on the same host/same hosting account and i link toys.net to biblesales.org (without linking from bible to toys) is that a valid backlink?
if another site links to you, then that's called a one way back link. If you then link to them afterwards, that's called a reciprocal link. One way links are better in my opinion as you don't give away any of your hard earned page rank.