Dynamic website rely on server side scripting to provided advanced interactivity and usually use a database to deliver the content for individual pages. A dynamic approach is appropriate for developing large websites with content which is formulaic, for example, catalogues, photograph albums and complex series of data. A dynamic website will be required to allow users to sort and search records, or to restrict access to parts of the website using a log-in procedure. Generating website pages on the fly, using a database to store and deliver content, is an efficient way of managing a large site, with maintenance and updating generally much easier than for a comparable static site. The disadvantage of dynamic website is that search engine optimisation techniques are more difficult to implement, particularly if the site’s search engine optimisation needs are not taken into account at the development stage.