So basically, the relevancy and rankings that a search engine imparts to your website will depend a lot on the number, quality and relevancy of incoming links to your website. There are some very specific things that I mean by the three adjectives which I have used in the last statement.

1. Number: The more the number of incoming links to your website the more highly it will be ranked by a search engine. However when counting the number of incoming links you should almost always focus on the relevant and quality ones.
2. Relevance: The more relevant the links are the more value your site has in the eyes of search engines. Relevancy basically means that the incoming links comes from a web page, which has content, related to the content on your web page. So for example an incoming link to this tutorial is more relevant if it comes from a SEO oriented website, as opposed to from a website for online gaming.
3. Quality: One another criteria, which goes into rating incoming links, is the age of the links themselves and the age of the site which houses those links. By age, I mostly mean the time when the Search Engine has discovered the link. The older the website (which houses the incoming link) the more weight the link carries. Please note that this is something, which is used mostly in Google and has little effect for rankings on Yahoo and MSN.

However some caution is required while proceeding on a link building campaign for a website. There are sites which will allow you to 'buy' incoming links from them. This is usually a waste of time and resources and these links do little to boost the popularity of your site. This is due to the fact that these sites are mosty unrelated to the content of your website and hence such incoming links are not valued much by search engines.

Moreover, some of these sites are specifically set up for the purpose of providing huge numbers of inbound links to different sites. Such 'link farms' distort the natural democratic process of link building which is more based on content relevance and association rather than on an overtly economic interest. Infact some search engines like Google have started black listing such 'link farms' and sites which are associated with them. As a result, such methods might do you more harm than good by getting your site blacklisted from Google's result pages.

There are still a lot of valid techniques you can use for link building. Read ahead and find out the best ways to boost link popularity of your site.

2. Site Optimization

Almost all Search Engines try to use a bit of natural language processing to understand the content of the website and related it to the search terms that they are fed with.. This association of keywords with websites is driven by keywords that appear at specific places in your website. For example:

1. Keywords that appear in the heading of a web page.
2. Words appearing in the link text of hyperlinks in a web page.
3. Words which are not common (like 'a', 'the' etc.) and which appear in high density in the sentences in the site.

Before looking at the specific Site Optimization techniques, understand the importance of targetting the right search terms.