What

Web Accessibility Definition:  "Development of information systems flexible enough to accommodate the needs of the broadest range of users...regardless of disability." — Cynthia Waddell

What are the Principles of Web Accessibility (POUR)? 

• Perceivable – available through sight, hearing, or touch
• Operable – compatible with keyboard or mouse
• Understandable – user-friendly, easy to comprehend
• Robust – works across browsers, assistive technologies (such as screen readers), mobile devices, old devices/browsers, etc. Follows standards.

How do they translate to what you do?

At a high level it means:

• content is well structured and clearly written
• links make sense out of context
• not relying on color alone to convey meaning
• providing appropriate alternative text for non-text elements (i.e., images and charts)
• helping users navigate to relevant content
• ensure accessibility of non-HTML content (PDFs, Word docs, Powerpoint files, etc.)
• providing headers for data tables
• users can complete and submit all forms
• captioning and/or providing transcripts for media

See the WebAIM Quick Reference: Web Accessibility Principles PDF for a quick, but comprehensive look at the principles and how they translate to what you need to do.