Link exchange is one of the oldest variants of capacity or performance puzomerok site TCI or PageRank. link exchange idea is that the site A link exchange with a site B and finally site owners expect to increase your site’s metrics. In practice, the exchange of links is rarely effective, since it is necessary to constantly monitor the to a site with your link there, and his performance did not fall. And, in fact to ensure that the resource owner does not put the link to your website. Ideally, to exchange links with sites that are strictly topical and limited exchange or do not keep it at all. And even better, when you link to Site A and the owner puts a link to your site from another of the resource.
But it is even better not to share links and do not buy them, and to write quality articles for the resource, and then make sure that the network they differed only with reference to your site.