The Role Of Navigability and Crawlability in SEO
There are so many important factors that count towards a success in search engine optimisation and there is a wealth of knowledge articles available to read on this topic. The two important factors I am going to discuss here today are navigability and crawlability. Although crawlability is generally the one which seems to be the one related to SEO, navigability also has a great impact on a website's search engine rankings. A site with good navigability makes it easier for search engines to find all important pages and content of that website.
How well can a search engine robot crawl a website has probably one of the biggest impact on a site's search engine rankings. An ideal website would have all its content accessible within 3 mouse clicks from the homepage. However this is not always easy. Still if it is used as a general rule, it can greatly help in making a website easily crawlable.
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The same problem arise with flash content. The robots cannot read them and as a result the content presented using flash will not be indexed. If you really want one version of your website in flash, don't forget to create an alternate html (crawlable) version. Mixing HTML and Flash is a better alternative though, provided you keep the HTML part for most of the more important content.
Image text is another issue. Robots are not humans. They cannot read image text (text presented as an image) and hence cannot index its content. The solution to this issue is easy; Images should be used for decoration and not as a text alternative.
Cookies are another culprit. Again the robots do not understand cookies language.
A very bad practice that some websites carry is "Fill the form (for example enter your email) to see the content". Again Spiders (Robots or crawlers) cannot fill forms to get through and see the content and as a result your most important part of the website (the content) is not crawlable. So a big NO to any such practice. (Exceptions are paid subscriptions and members only stuff).
Navigability of a website
Navigability can be defined as the accessibility of a website from any page a user might land on. For a business website it would mean that no matter which page a user lands on, it would drag him towards what it sells. Whatever the website is aimed for, navigability necessarily means providing appropriate links on virtually any possible landing page, to the rest of the website. To be more specific, any page of the website which can be indexed by a search engine should have links to the rest of the website.
For common and general pages of any website, you won't normally find any navigability problem as every good website have links from all the main pages to the rest of the website. But there are still pages where navigability is a problem for your website. These pages include pop up information pages, small script pages and technical support pages etc. Often for the sake of keeping the more important or main page, additional information is provided in a pop up window. In such case, if the pop up crawlable (as a discussed above) and the search engine spider can index it, then it is important that you put a link on it to the homepage of the website otherwise if the page is found on the search engine and is being visited by someone, it will be very hard to navigate the rest of the website.
A similar problem can arise with websites having technical support pages provided separately. Often technical support pages are designed separately and do not contain the main navigational links. It is again strongly recommended that a link be put to the homepage on all such pages.
In brief anything crawlable in the website should also be loaded with navigable links to the rest of the website or at least the homepage of the main website.