Link building
Google became the world's dominant search engine due to the relevancy of its SERPs.
This relevancy was a direct result of Google's usage of Page Rank to determine its SERPs rankings, so it was only natural for the other major search engines - Yahoo and MSN - to follow suit and start to base their SERPs rankings on Site Citations, as well as Site Content.
Unfortunately, though, the importance of inbound links for a site's SERPs rankings led to an over-emphasis on the gaining of inbound links, by web site owners and search engine optimisation practitioners.
The practice of "gaming" the search engines became widespread, with initially simply the quantity of inbound links being the deciding factor in a site's SERPs ranking.
Link Builders appeared from everywhere, who offer to generate multiple inbound links to your site for a fee, often based on the number of links they generate.
A further obsession with Page Rank ensued, with the Link Builders only aiming to generate inbound links from pages with a Page Rank of 5 or above.
Again this contributed to the self-perpetuating nature of Page Rank, with more and more web site owners simply getting links from other sites in order to increase their own Page Rank.
Reciprocal links are the primary method of link building - i.e. "you link to me and I'll link to you" - and have led to a huge number of emails being sent between companies that state "We have placed a link to your site on our links page - please do the same to our site".
What works best now, though, is not simply the quantity of inbound links, or even the quality or relevancy.
It is a combination of a range of types of links, which the search engines could assume to have been developed in a "natural" fashion.
e.g. it is unlikely that a site will generate several quality, relevant links from its inception, without having either bought them or traded them in some manner. Google in particular may consider this to be "Over Optimisation" (see the Over Optimisation section), and "penalise" the site accordingly.
Range of Links
A practical method of generating sufficient inbound links to achieve a good SERPs ranking is detailed below:
1) Ensure your site has valuable content, that other sites will wish to link to. This is one of the most successful methods of generating inbound links - the vast majority of which will be 1-way links.
2) Research the "credible" and "authoritative" sites within your chosen subject area (see the Credibility and Authority section). Approach them for a link - you may have to give them a reciprocal link in exchange.
3) Generate complementary links from sites that can be seen to be relevant to your site's visitors. For instance, the V&A site is aimed at anyone who is interested in art, design, fashion etc. These people may find information about various other art forms useful. Thus seeking an exchange of links with a site dedicated to other art forms will be seen to be useful for both yours and their site visitors. Happily, this also "boosts" your site in the SERPs.
4) Generate directory links from the free and paid-for directories. The search engines assume this is what any site owner would wish to do and thus will "boost" your site's rankings accordingly.
5) Generate non-relevant links with "partner" or "supplier" sites. Again, this is seen as being a perfectly natural thing for a web site to do - e.g. linking to your stationery supplier or a retailer of your products, and receiving a link back.
In general, the more links the better is still a principle that holds true - though it is far better to achieve a few quality, relevant links, through having unique, quality content, than to achieve hundreds of non-relevant links from general sites.
