A one way (inbound) link refers to a website linking to you, but you not linking back to it. Search engines will generally credit your site with the most importance for this type of link (compared to 2 way and many way links), so this is what to aim for. The quality of the site, Pagerank and context of the surrounding text are all very important though – there’s little point in paying for link building services to post links to your website on hundreds of low quality random directories, as this will achieve little. In fact, Google states that it may penalise you for buying links to artificially manipulate your Pagerank. It’s much better to have a few high quality links featured on relevant, respected websites amongst content related to your core business. Perhaps the best way to acheive this is through article campaigns. Of course, aside from the importance search engines attribute to them, links on other websites are themselves a source of traffic, so it’s best to have a link to your website in a useful place where users will actually follow it. Other techniques to create inbound links and increase traffic include: press releases, social media, RSS feeds, (external) blogs, paid advertising and email campaigns. It’s worth familiarising yourself with the available techniques and choosing a combination that suits your subject matter and budget.
2 way links
A two way link refers to a website linking to you and you linking back to it. This is often a result of link exchanges and this is the reason why search engines see two way links as less valuable. If the only reason a link is present on a website is to boost the recipient site’s rankings, there’s little benefit to it. Article exchanges can also result in two way links, but there’s more value in this, since the article is providing the user with some benefit. Since article exchanges generally involve the links being found in context, amongst relevant text, search engines will generally credit these links with more importance than a link in a page full of links.
Many way links
Some link exchange services work with a series of websites that link to one another with the intention that search engines won’t see them as two way links and credit the links with less importance. For example, A links to website B, links to website C, which links back to website A. Search engines will recognise this and count as less important than one way links.