Websites that have databases which can make content into a web page with the use of a dynamic script like PHP or JavaScript is considered to be dynamic websites. Dynamic websites are increasingly popular, and many websites choose dynamic content over static content. This is because if a website has thousands of pages, writing or updating each static page by hand is a monumental task and very time consuming.
There are two types of URLs: dynamic and static. A dynamic URL is a page address that results from the search of a database-driven website or the URL of a web site that runs a script. In contrast to static URLs, in which the contents of the web page stay the same unless the changes are coded into the HTML, dynamic URLs are generated from specific queries to the database. The dynamic page is basically only a template in which to display the results of the database query. Instead of changing information in the HTML code, the data is changed in the database.
Dynamic URLs often contain the following characters: ?, &, %, +, =, $, cgi-bin, .cgi.
There is a risk when using dynamic URLs: they are not search engine friendly. For those at most risk of losing search engine positioning due to dynamic URLs are internet forumss, e-commerce stores, sites using content management systems and blogs like Mambo or WordPress, and any other database-driven websites.
Static URLs typically ranked better in search engine results pages, and they are easier and faster for search engines' web crawlers to index than dynamic URLs, if dynamic URLs get indexed at all. Static URLs are also easier for the end-user to view and understand what the page is about. If a user sees a URL in a search engine query that matches the title and description, they are more likely to click on that URL than one that doesn't make sense to them.
Another issue is that dynamic pages generally do not have any keywords in the URL. It is very important to have keyword rich URLs. Highly relevant keywords should appear in the domain name or the page URL. This became clear in a recent study on how the top three search engines, Google, Yahoo!, and Bing, rank websites.
The study involved taking hundreds of highly competitive keyword queries, like automotive, fashion, and computer software, and comparing factors involving the top ten results. The statistics show that of those top ten, Google has 50 percent of those with the keyword either in the URL or the domain; Yahoo! shows 60 percent; and MSN has an astonishing 85 percent. What this means is that to these search engines, having keywords in URL or domain name could mean the difference between a top ten ranking, and a ranking far down in the search results pages.
Dynamic pages shouldn't be created for pages that the website want search engines to crawl. Mod Rewrite or URL rewriting tool can be used to anticipate this. All dynamic URLs in a website should be changed to static URLs to avoid penalties by search engines due to having duplicate URLs. Altering the Robots Exclusion Standard File file can prevent search engines to crawl duplicated URLs that are made.