One of the most important things for a visible website in the search engine is the site architecture. The Site architecture design includes a web site's navigation scheme and how the items on pages. Alexander (2002) states that site architecture in SEO is very important, because the search engine spiders must be able to find and record the keyword-rich text on your web pages. And without effective site architecture, web site marketers must pay for search engine visibility through paid inclusion or pay-per-click programs. There are a variety of navigation architecture options follows.
Text based Links
Many website designers said that all search engines spiders successfully interpret text links because they can understand the text in and outside the link and follow these links from one to another webpage. Website visibility experts also suggest that the use of text links is very important for visible web pages in search engine, because they provide the target audience valuable information about visited and unvisited pages (Nielsen 2000). too many text links on a webpage can make the keyword density less effective. Keyword prominence can be retained by the use of bread-crumb links (Aguillo 2000). He also states that if there are more words in the text links of a given webpage than in the main body content, the web designer should using graphic images as part of the navigation scheme. A navigation scheme based on text-links might seem like an ideal solution because all the search engines prefer this type of link. A web page full of text-link tends to download much faster than a web page full of graphic images.
An image map is single graphic image that enables users to access different web pages by clicking different areas of the image. An example is a graphic image of a country map, where different geographical areas provide links to weather forecasts for each individual area (Weathersa 2004).
According to Whalen (2003), some search engines do not follow the links inside the image map because the reason of spam. Furthermore, search engine spiders assess the main body text on a web page with more ease if the navigation scheme is a single graphic image rather than multiple ones. A single image downloads very quickly than multiple graphical images. It is not yet clear which one provides the best value.
Flash animations provide a very effective way of developing web pages with visual elegance. Web designers use this technology because it shows a way to develop Flash movies, vector images, and Flash animations.
According to Munafo (2002), Design with flash has benefits for web designers and for site visitors as well. With the Flash navigation schemes some time contain little text for search engine crawler towards index. Thelwall (2000) tells that a splash page consists of little or no text for search engines spiders which they follow. Some splash pages consist of a redirect instruction when the Flash animation has terminated - some search engines take redirections as a spam.
Thurow (2002) claims:'If you want to keep the flair and ambiance of Flash movie, place the text and links below the fold'.
Windows pop up,
Validation of form,
Drop down menus.
Dynamically Generated URL's
Marketers of search engines realise that inside the dynamically created web pages search engines cannot follow the links, and they always feel very difficult to advertise and make them search engine friendly. And they always have difficulty in interpreting the URL which used to retrieve web pages (Aguillo 2000). There are examples of some symbols that are not search engine friendly, that are the indicators of dynamically used content which includes: ?, &, %, and $. The dynamically created web pages have URL's which always contain some of these kind of characters. Ollins (2002)
Thurow (2002) suggest that are dynamically generated URL's which could easily trap search engine crawlers and make them to crash. He further writes that search engines update their indexes after four or eight weeks. If they conclude dynamically generated URLs in the search results, the data might change in between the time they search earlier the URL and the time of the URL shows in the search results. The results obtained in search engine by the users will regularly be out of date.
Sullivan  tells a number of workaround which can make dynamic web site more search engine friendly . Which include:
In the URL minimize the number of parameters
Always add static information,
Add HTML pages which search engines can index easily,
In the URL modify the stop characters
Utilise pay-for-inclusion (PFI) programs,
Participate in pay-for-placement (PFP) advertising.
The one of the big advantage of using drop-down menus is a saving in screen. The drop-down menu does not have a space like a series of text links or navigation buttons (Whalen 2003). Nielsen claims that screen real estate is valuable, and if a little place should be sacrificed to the navigation scheme-original content should capture the most prominent place (Nielsen 2000).
Navigation and Frames
The uses of frames help web site designers to provide a user friendly navigation scheme for users, for example when user holding up a one side of screen and the other can scrolls up or down. Search engine crawlers will index text and then follow the links in, for example a navigation frame, The initial code of frameset does not show keyword rich text to index and set links for crawlers. Murata( 2003).
He also told that when a site uses a frames based design, it must always include keyword rich links and content for the most important pages in the website, so the crawlers can remember the most important text.
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