This article explores the critical importance of designing inclusive web applications with accessibility in mind. It delves into the ethical, legal, and business imperatives driving the need for accessible web design, highlighting that over one billion people worldwide live with some form of disability. The article discusses key accessibility standards, particularly the Web Content Accessibility Guidelines (WCAG), and outlines essential techniques and tools for implementing and testing web accessibility. These include semantic HTML, ARIA roles and attributes, color contrast considerations, keyboard navigation, and alternative text for images. The article also examines various testing tools such as Lighthouse, WAVE, axe DevTools, and screen readers. Furthermore, it presents a compelling business case for accessibility, emphasizing benefits such as an expanded user base, improved SEO, enhanced brand reputation, and legal compliance. Through comprehensive exploration of these topics, the article underscores that accessibility is not just a regulatory requirement but a fundamental responsibility that leads to better digital experiences for all users