Important points to understand to achieve measurable, quality results.
W3C standards lay down the laws of the Internet for how to code a perfect site.
A website that adheres to W3C standards will be more likely to work in multiple browsers, multiple monitors, mobile devices, which means you get to reach a wider audience.
It will also be smiled upon by Google and accordingly highly ranked by the search engines, meaning you will get more visitors to your website.
A website that adheres to W3C standards will be accessible through Internet tools and devices such as screen readers (which enable visually impaired users to access your website) which means you can reach all of your potential customers.