In web development, what is a commonly used tool for validating HTML and ensuring compliance with standards?

The W3C Validator is a widely recognized tool for validating HTML and ensuring compliance with web standards established by the World Wide Web Consortium (W3C). This online service allows developers to submit their HTML code and receive feedback on errors or warnings, helping to identify any issues related to conformity with HTML specifications. By using the W3C Validator, developers can improve the accessibility, usability, and performance of their websites, ensuring that they adhere to best practices in web development.

While the HTML Linter also serves a similar purpose by examining HTML code for potential errors and coding style issues, the W3C Validator specifically focuses on checking standards compliance. Similarly, the CSS Validator is dedicated to validating CSS code, and a Markup Checker is a more generic term that may not specifically refer to a recognized, standard-validation tool like the W3C Validator. Thus, the W3C Validator is the definitive choice that embodies the standards compliance aspect in web development.