The internet is a wash with information about everything from aardvarks to the film Zulu. As the various search engines crawl over your website they will look at two aspects which help greatly to get your site ranked, site links and content (which I can’t stress enough is so important).
Once they have found these two main attributes then will then look at all of the descriptive information about each page on your website. The algorithms are that now that advanced they will be able to determine whether or not your website and content is relevant for users that may do a search based around your website.
Also another factor that is taken into consideration is the type of links that are pointing to your website, i.e. if your website is selling business stationary you would maybe go for the term ‘business stationary, sale now on’, links need to be relevant to your site and the text within the links, also known as anchor text has to match your content especially if you wanted to get ranked well.
Also the website that the link is coming from needs to be trustworthy for it to be granted a good link, so a link from the BBC News website would be invaluable as the search engines see this as a very important website. If your website had a link from Simons Scissor Shop Site, for example, then the search engines will look at this and not give this much importance.
Let’s pause for a minute and look at an example. I’m a Freelance SEO based in Nottingham; I wouldn’t try and promote the website at selling pizzas. If I did the algorithms would look at many different factors and decide that my website has no relevance to selling pizzas and in turn would not rank me for this.