BBC News writes in The Secret Of Making Things Work:

With thousands of products and services to choose from, ease of use is still a bonus factor rather than a norm and those that possess this elusive quality often go on to dominate markets.

Google, Amazon and eBay are successful brands not just because of their financial models but the ease with which their users are able to achieve their goals on these sites, be they searching, buying or selling… …Such examples of good practice are invisible to most consumers, but the bad stick in the memory.

How many people, while trying to book a holiday online, have got one detail wrong on the form, only to see that it has deleted all the details and dumped them back to the beginning?

A company’s “brand” does not just mean their logo or icon, but the gut feeling a customer gets from their products. This gut feeling is communicated by many elements including what the company says about itself, its advertising and, of course, the ease of use of its products…

…Positive experiences with products and advertising seek to remind you of a brand’s good qualities, and this responsibility has shifted away from marketers and advertisers, thanks to work done years ago by the pioneers of usability.