What is usability?

The International Organization for Standardization defines usability as,

The extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use.

Usability vs. accessibility: what's the difference?

It is important to remember that just because a site is accessible does not mean it is usable. 

Accessibility initiatives aim to make the Web accessible by removing the barriers that make it difficult or impossible for people with varying levels of disability to use the Web.  

Usability can be measured by how well users, with or without disability, are able to understand, navigate and interact with the site. In addition to being efficient and effective, usability measures include user engagement, ease of use and error tolerance. 

Usability resources


International Organization for Standardization

Standard ISO 9241-11:1998 provides guidance on usability.

UserFocus usability guidelines

A London-based usability consulting and training company.


Book cover Don't make me thinkDon't Make Me Think: A Common Sense Approach to Web Usability
by Steve Krug

A great book for conveying what web usability is about. This book offers straightforward descriptions and examples.


Book cover Letting go of the wordsLetting Go of the Words: Writing Web Content that Works
by Janice (Ginny) Redish

Best book addressing web content and usability – that is, how to write web content that is usable/user friendly for website visitors.

Book cover Communication designCommunicating Design: Developing Web Site Documentation for Design and Planning
by Dan M. Brown

A book that’s useful for those who are project managers and need to understand what deliverables are key to creating a usable website.

Quick tips

Characters per line

Line lengths should be neither too short (<50 characters per line) nor too long (>100 characters per line) when viewed in a standard browser width window.


All corporate information should be grouped in one distinct area (e.g. "About ____").

Navigation labels should contain the "trigger words" that users will look for to achieve their goal.

There should be no more than 7-9 navigation items per menu/sub menu.

There should be no more than three levels of navigation in the main navigation.

There should be no external links in the main navigation (this includes other University of Waterloo sites that are not the website the user is currently on).

Trust and credibility

The content is up-to-date, authoritative and trustworthy.

It is easy to contact someone for assistance and a reply is received quickly.

The site is free of typographic errors and spelling mistakes.