As an emerging technology, the Web is full of unique challenges for developers, designers – and engineers. Its use for increasingly complex applications such as e-commerce and banking, involving connection to many data sources, highlighted a number of common difficulties. During the design phase, good modeling of complex sites is difficult; during implementation, the design models are often found to be difficult to translate into an implementation model; afterwards, maintenance and long-term management of the site’s evolution offer problems of their own. Qualities such as integrity, security, and usability are often afterthoughts, or left unconsidered – most particularly during the site’s post-deployment evolution. Many organizations working for the Web still use ad-hoc, chaotic development and maintenance methods, even though the issues surrounding development are now widely known.