Search Engine Optimisation (SEO)
If your website is to attract visitors it needs to be found on search sites like Google, Yahoo and Bing. Most people searching only look at the first 2 or 3 pages of results on the SERPS (Search Engine Results Pages) and it is therefor benefficial, even critical, for your site to be ranked highly. The process of ensuring this is SEO.
The first search engines simply looked for keywords
in the indexed pages but Google introduced the idea of
using the number of incomming links (backlinks) to rank
the pages by popularity or authority.Today, many different
components are used to rank pages in search results but these are still the main ones.
As Google has become the dominant search engine, it is wise to optimise web pages with it's methods in mind.
The number of websites constantly grows and search engines need to filter out those of low quality. In 2011 Google launched Panda, it's new search algorythm, to address this. In April 2012, google launched the Penguin update. This penalises sites that have been over-optimised, using SEO tricks rather than value to visitors to rank highly. This was toughened up further by Penguin 2.0 in May 2013. Any SEO techniques that Google does not approve of will now cause a website serious problems with it's ranking in SERPS (Search Engine Results Pages). If an SEO "expert"claims they can guarantee high rankings it is likely they will use risky "black hat" methods that may work in the short term but risk the site being heavily penalised later. The latest (Sept. 2013) Google algorythm is "Hummingbird". It consideres over 200 components (like Page Rank, incomming links etc.) This attempts to understand more conversational type queries and their context rather than just keywords, making SEO more difficult. Optimising for specific keywords is now less effective and it is the quality and relevance of content that matters more. The authority of the site, measured by the quality(not quantity) of backlinks is still a major factor in ranking.
There are several aspects of a web page that affect search rankings. These can be split into two types, coding and content.
The coding aspects are to ensure the search engines understand what the web pages is about and what the main keywords are. It also ensures the site performs correctly across a range of web browsers and oporating systems. Each page needs a unique title and description, each image needs an %alt; description and possibly a title. Images should also be web-optimised to keep file sizes down. The page needs to be compatible with all current operating systems,web browsers and screen sizes, and made sure to be accessible for people with various disabilities. Links to external sites should generally be marked "no-follow". It is best to include a "robots.txt" file and submit a site map to leading search engines.
The content of the web page consists of text, images and possibly video. The process of optimising these is known as Content Management. The text needs to be easily understood and be on a single topic, with the appropriate keywords and similar words used quite frequently but in a natural way. Keyword stuffing, though, is considered a "black hat" technique an must be avoided. It is essential that the text is unique, not available on another web page. Headers should include the main words as these have higher weighting than general text. Images can enhance both user experience and rankings:it has been shown that pages with images have a higher success rate at goal conversion (eg sales) than plain text pages. Video takes more to create but works even better than images, especially if it appeals to a wider audience and gets shared through social media (YouTube, Facebook, Twitter etc.).
A major factor in SERPS position is the quality and number of in-coming links (backlinks).
In the past, the number of links was important and many site owners paid for 1000's of low quality links. This can now be penalised so should be avoided. Acquiring good quality links is a slow, difficult process and requires good page content. These links can be from trade organisations, related sites, some directories and aquired via social media or having usefull content.