Why is it important to validate HTML and CSS code?

Validating HTML and CSS code is crucial because it ensures that the code adheres to established web standards. This adherence helps prevent various rendering errors across different web browsers, leading to consistent and reliable user experiences. When code is valid, it is more likely to be interpreted correctly by web browsers, thereby reducing the risk of display inconsistencies and functionality issues. This is particularly important in web development, where numerous browsers and devices are used to access websites, each with its own rendering engine. Consequently, when developers follow standards through validation, they help create more robust and compatible web pages.

While enhancements to aesthetics, loading speed, and search engine rankings can be benefits of well-structured code, they are not the primary purpose of validation. The focus of validation is primarily on maintaining code quality and improving cross-browser compatibility, which indirectly supports those other areas rather than addressing them directly.