Link building lies at the heart of most search engine optimisation (SEO) campaigns. Although it is important to ensure that everything on a website is optimised for search engines, it is even more important to ensure that a website lies at the centre of its own network of inbound links. Search engines rely on counting links to determine the authority of a particular website, and this affects its ranking position within search engine results pages (SERPs). By ensuring that a website has a considerable volume of high-quality inbound links, an SEO professional can elevate that site within the SERPs.
There are, of course, many different approaches to link building, some of which are more respectable than others. At the very bottom of the pile are illegal link building practices, such as hacking into authoritative websites and manipulating these to contain links back to a website that is being promoted. Most professionals would never risk their reputations or freedom by engaging in such practices, but some who are already involved in marketing illicit pharmaceutical or pornography sites see little to lose by breaking the law. These illegal and unethical techniques are widely known as 'black hat'. The black hat label also covers some particularly unethical but not quite illegal processes, such as manipulative cloaking and JavaScript redirects.
A little further up the chain are techniques which are generally considered unethical but are not illegal. These methods are known as 'grey hat', and a large number of link building professionals touch upon them, although they should be avoided wherever possible. Perhaps the most common of all grey hat techniques is purchasing links. Professionals (and amateurs) who engage in this practice produce original pieces of content content purely for the purpose of containing links. These pieces are then distributed to bloggers, and perhaps other website owners, who agree to host them in exchange for a fee. Although this practice contravenes the webmaster guidelines laid out by Google and other search engine operators, it is extremely difficult to detect and widely tolerated so long as it is not taken to an extreme.
Methods of link building which cannot be regarded as immoral or illegal fall into the laudable 'white hat' category. This is link building in the true spirit of the world wide web. Professionals that are involved in white hat link building develop relationships with other webmasters whose sites share common ground with the website that is being promoted. Unlike other methods of link building, this approach rarely produces instant results. After a relationship has been cultivated, white hat link builders offer to write a guest post or similar piece of content for inclusion on the other website. In exchange, they request that the piece include a link back to the website that they are promoting.
Although this type of link building is difficult to attain, it can often be the most rewarding and sustainable in the long run. Other link building techniques are not supported by search engine operators, who are continually introducing measures to counteract them. White hat link building is search engine approved, which means ranking gains made in this way are rarely lost overnight. Links gained through the production and sharing of original, high-quality content are also more likely to come from high-profile, authoritative domains than those which can be readily bought.