May 11th, 2010 by Mike

Accessibility means making a website easy to use for as many people as possible, and this can only be a positive factor for SEO in the long run. Since search robots rely upon text to extract information from sites, what is visible to them resembles what is ’seen’ by screen reading software used by visually-impaired surfers of the Web. The aim of search engine optimisation involves making web pages readable for search robots, so that information may be extracted and used in search results. Principles that improve accessibility in general tend to make a website more crawlable for search spiders at the same time.

Correct HTML, with heading tags to establish structure and emphasis within a page of text, and separate CSS files for styling, helps search robots extract meaningful information and creates a better experience for all visitors, with smaller page files which are quicker to load. A clear system of navigation with logical, hierarchical flow and descriptive link text makes life easier for users and helps search robots find and index all the pages on a site.

Where images are concerned, it is good practice for accessibility always to include some text within an ‘alt’, or alternative text, attribute, describing what the picture contains. This is useful for everyone should images fail to load for some reason. It is essential for visually-impaired visitors, as their screen reading software can then read out the information, giving a better sense of the page as a whole, and it is extremely useful for search robots that have no other way of determining what the image is apart from any clues contained in the file name or surrounding text.

Progress is being made in the ways search crawlers are able to evaluate images, and they may recognise the proportions of different coloured pixels, giving an indication that, for example, there are excessive amounts of flesh tone on certain sites, but they are a long way from being able to see as humans do. It is not yet possible for search robots to recognise words which are presented in the form of an image, although that could be remedied in the near future. That is why it is important to ensure all significant information on a website is in the form of text.

Flash files and JavaScript are not readily understood by screen readers or search robots, so any content which is vital for a website to function should not be displayed this way. Search crawlers are beginning to be able to extract some text information from Flash, but this is far from being able to comprehend the files fully.

A useful way of simulating how web pages appear to search crawlers, or screen readers, is to use a text-based browser such as Lynx. An experienced SEO company will view sites this way to determine which parts of a page are visible to search robots.

At SearchEngineOptimization.co.uk we can make sure your website is fully accessible to search engines and visitors alike.

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