Different from a hard-coded static HTML site, a dynamic website is one where the web pages are created on demand based on specified criteria that pulls together information from a database.
Optimizing dynamically generated web pages for search engines ensures they can be scanned and indexed by the search engine bots even though they are created on demand.
Of particular importance is the naming of dynamically generated URL strings. Keeping the strings free of characters that do not represent spoken language allows search engine bots to easily follow the url to get to the actual website content. It is also a good idea to include relevant keywords and phrases in the url.