Webmasters often overlook code validity, especially due to design specifics, and few are concerned about it. After all, what difference does it make if the code is valid or not, as long as the website works fine in browsers?
However, that’s not entirely true. Before deciding to keep non-valid code on your site, consider the following:
Search Engine Preference: Valid code is favored by search engines. While they may index your site even with unique content, there’s no guarantee it will always happen.
Browser Differences: When browsers encounter errors on a site, they interpret them differently. Some skip errors, some render them as is, and others fix them. Achieving a consistent appearance across all browsers requires understanding how they treat errors, which is almost impossible.
Client Requirements: Clients often request websites with valid code, as it’s seen as a measure of a developer’s professionalism. However, their understanding of this is usually limited.
Chasing 100% Valid Code: It’s essential for the code to be valid as much as possible. Yet, remember that besides official HTML standards, there are unofficial standards that help expand a site’s capabilities.
One example is Schema.org’s microdata. It can create appealing snippets and provide additional information to search engines, which is a significant advantage. However, using microdata leads to invalid code.
Therefore, strive for valid code, but understand that errors are sometimes acceptable.