A backlinks means both 1-way links as well as reciprocal links/3-way links. But I guess you meant reciprocal links only while stating backlinks. Reciprocal links are as good as dead for long time now. Though some sites still use them and have claimed that its helping but I personally have stopped doing them for our clients for 3 years now. 1-way links are much better. The thing is simple google is smart and if you do stuff like I scratch your back in return you scratch mine-such things will never get credit with google. Also there is risk of getting penalized/banned if you do reciprocal links in the wrong way(linking to banned sites or to sites totally unrelated to yours). Remember one way links can never harm you at least since no one can have control over who link to them but reciprocal links have the risk since one has full control over who they link to.