This document introduces web standards and accessibility. It discusses how Jeffrey Zeldman and the Web Standards Project advocated for standards to make websites more accessible, compatible across browsers and devices, and sustainable over time. The document explains key standards like XHTML, CSS, and DOM that separate website structure, style and behavior. It also outlines why standards help with accessibility, device independence, performance and more. Finally, it provides an overview of different types of disabilities that standards aim to support, such as visual, motor and cognitive impairments.