Cross-browser accessibility is essential for ensuring that websites are usable by a diverse range of users, including those with disabilities and those using different devices and browser versions. Accessibility testing involves verifying that websites are navigable and understandable for individuals using screen readers, alternative input methods, and various assistive technologies. Key components of accessibility include semantic HTML structures, keyboard navigability, alt text for images, avoidance of hidden content, appropriate color contrasts for colorblind users, and closed captions for videos. Ensuring cross-browser compatibility is crucial, as some HTML tags and features may not work uniformly across all browsers. By addressing these accessibility aspects during development and testing, websites can significantly enhance their reach and user experience for all users.