Web accessibility is crucial in ensuring that websites and web applications are usable by all users, including individuals with disabilities. A web accessibility checklist for developers outlines best practices and standards to follow, such as providing alternative text for non-text content, keyboard accessibility, proper color contrast, easy navigation, etc. Web Content Accessibility Guidelines (WCAG) provide four principles: perceivable, operable, understandable, and robust. These guidelines are classified into three levels of compliance: A, AA, and AAA. Following a web accessibility checklist ensures that websites or apps align with WCAG standards and create an inclusive online experience for everyone.