What is Search Engine Optimisation?

Search Engine Optimisation is divided in:

Onsite Search Engine Optimisation
Onsite Search Engine Optimisation is a term used for a set of tasks that make a web site ‘Search Engine Friendly’.

For the web site to appear in the search engine results page (SERP) for a chosen search phrase, the following must occur:

1. The web page needs to have the content relevant to that keyword. Basically is a page is about ‘SEO’ and the target search phrase is ‘SEO’, the page has to have the word ‘SEO’ used on the page.

2. Since web page is probably not the only one that contains the chosen keyword ‘SEO’, that keyword should appear in the page multiple times in the text, and other page elements like page title, the web address of the page, the alternative text for the images on the page, formatted in different styles…

3. Google must be able to access your page (check your robots.txt).

4. Google must be able and ‘helped’ to find your page to be able to index it’s content (submit your page to Google, submit your Sitemap as well).

5. The content on your page must be readable by Goggles indexing engine aka ‘Spider’ – Text is what it likes, it doesn’t not read the text on images, animations, etc.

6. Web site structure depends mainly on the software that was used to create your website, and the options chosen in it. Some tools generate sites that are well structured for the search engines and are ‘OK Out of the Box’. The majority of the content management systems have not been built with the SEO in mind and do not generate a search engine friendly sites. Therefore the rework is required to make them more friendly. The most common is the URL rewriting – where the URL are changed from the URL that contains numbers to the ID that contains relevant keywords.

7. Google also lets webmasters submit a Sitemap of the site, and determine what geographical market the site is targeting (no for local country domains like ‘.ie’ that can be targeted only towards Ireland or the respective country like ‘.co.uk for UK, etc). Google Webmaster Tools has a number of other features helping you to work on your web site optimization.

Offsite Search Engine Optimisation
Offsite Search Engine Optimisation is much simpler than onsite and it consists of creating links towards your site from other web sites called Inbound Links. There are number of quality elements of the inbound link:

Does Google ‘see’ the Inbound Link?
the most important one is that the link is placed on the page that Google has in its index, and has re-indexed the page after your link was placed.

Link Text
The second most important element is the text used to generate the link, since if it contains the keywords relevant to your site, Google will rank your site higher for the same keywords.

Page Importance (Google PR)
A link from a page that has many inbound links is worth more than a link from a page with no or a small number of inbound links. Google assigns a score called a Google PR to every page in its index on a scale from 0 to 10. Search engine optimizers will argue that the link from a high PR site can bring more benefit than hundreds of links from a low PR sites.

Number of links on the site linking to you (Link Juice)
The less outbound links (link to other web sites) on the site linking to you – the more value will the inbound link bring to your site. There are number of theories on how pages ‘Pass’ the Google PR to each other via the links, but in general, you can be sure that your site will get from 1/3 to ½ of the PR value from a page where a link to your site is if it is the only outbound link to your site. How do many of those inbound link values add up to generate a Google PR of your page is a mystery!

The definitions of the Search Engine Optimisation from the Web:

Wikipedia:

Search engine optimisation (SEO) is the process of improving the volume and quality of traffic to a web site from search engines via “natural” (“organic” or “algorithmic”) search results for targeted keywords. Usually, the earlier a site is presented in the search results, or the higher it “ranks”, the more searchers will visit that site.

Google:

SEO is an abbreviation for “search engine optimizer.” Many SEOs and other agencies and consultants provide useful services for website owners, from writing copy to giving advice on site architecture and helping to find relevant directories to which a site can be submitted.