Is a reciprocal link still useful?
Links are called « reciprocal » when a page A sends out a link to a page B and page B sends out a link to this same page A.
This behavior is typical of websites practicing link exchanges in order to optimize their SEO. Search engines would therefore try to identify this kind of method aimed to artificially increase the popularity.
However, this doesn’t mean that the evaluation of reciprocal links becomes null.
Furthermore, Google many times reminded us through their ex-star engineer Matt Cutts that there are natural reciprocal links.
A systematic penalty would therefore makes no sense because it would not be systematically legitimate.
Some SEO professionals avoid reciprocity by working on 3 websites and thus creating non-reciprocal links in the shape of a triangle.
Website A is pointing to website B which is pointing to website C which is pointing to website A.
The logic is undeniable but given the power of computing used by search engines and the creativity of their engineers, we can imagine that this kind of trivial linking remains easily detectable.