Nielsen Norman GroupEvidence-Based User Experience Research, Training, and Consulting
Usability is a quality attribute that assesses how easy user interfaces are to use. The word "usability" also refers to methods for improving ease-of-use during the design process.
Usability is defined by 5 quality components:
Usability 101: Introduction to Usability
First Rule of Usability? Don't Listen to Users
Teens are (over)confident in their web abilities, but they perform worse than adults. Lower reading levels, impatience, and undeveloped research skills reduce teens’ task success and require simple, relatable sites.
What is usability? How, when, and where to improve it? Why should you care? Overview answers basic questions + how to run fast user tests.
Sites have improved, and we now know much more about e-tailing usability. Today, poor content is the main cause of user failure.
The ten most egregious offenses against users. Web design disasters and HTML horrors are legion, though many usability atrocities are less common than they used to be.
The 10 most general principles for interaction design. They are called "heuristics" because they are more in the nature of rules of thumb than specific usability guidelines.