What is the most effective way to ensure web page code adheres to W3C standards?

The most effective way to ensure that web page code adheres to W3C standards is to visit external validation sites or use built-in validators. These tools are specifically designed to check the correctness of HTML, CSS, and other web technologies against the defined W3C standards. They provide immediate feedback, highlight errors or warnings, and suggest fixes, which helps developers ensure that their code is compliant and functional across different web browsers.

Using validation tools can significantly streamline the development process by offering automatic checks that may not be catchable by a simple review or debugging process. This ensures the code not only meets standards for proper syntax and structure but also helps in maintaining accessibility and SEO best practices.

Although consulting peer reviews, using debugging tools, and reading documentation all contribute positively to the development process, they do not provide the dedicated focus that validation tools do in ensuring adherence to W3C standards. Validation sites and built-in validators are specifically tailored for this purpose, making them the most effective option.