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Usability 101: Introduction to Usability

byJAKOB NIELSENon January 4, 2012

Topics:

  • Human Computer Interaction

Summary:How to define usability? How, when, and where to improve it? Why should you care? Overview defines key usability concepts and answers basic questions.

This is the article to give to your boss or anyone else who doesn't have much time, but needs to know the basic usability facts.

What— Definition of Usability

Usability is aquality attributethat 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 by5 quality components:

  • Learnability: How easy is it for users to accomplish basic tasks the first time they encounter the design?
  • Efficiency: Once users have learned the design, how quickly can they perform tasks?
  • Memorability: When users return to the design after a period of not using it, how easily can they reestablish proficiency?
  • Errors: How many errors do users make, how severe are these errors, and how easily can they recover from the errors?
  • Satisfaction: How pleasant is it to use the design?

There are many other important quality attributes. A key one isutility, which refers to the design's functionality: Does it do what users need?

Usability and utility are equally important and together determine whether something is useful: It matters little that something is easy if it's not what you want. It's also no good if the system can hypothetically do what you want, but you can't make it happen because the user interface is too difficult. To study a design's utility, you can use the same user research methods that improve usability.

  • Definition: Utility = whether it provides thefeatures you need.
  • Definition: Usability = howeasy & pleasantthese features are to use.
  • Definition:Useful = usability + utility.

WhyUsability is Important

On the Web, usability is a necessary condition for survival. If a website is difficult to use, peopleleave. If thehomepagefails to clearly state what a company offers and what users can do on the site, peopleleave. If users get lost on a website, theyleave. If a website's information is hard to read or doesn't answer users' key questions, theyleave. Note a pattern here? There's no such thing as a user reading a website manual or otherwise spending much time trying to figure out an interface. There are plenty of other websites available; leaving is the first line of defense when users encounter a difficulty.

The first law ofe-commerceis that if users cannotfindthe product, they cannotbuyit either.

Forintranets, usability is a matter ofemployee productivity. Time users waste being lost on your intranet or pondering difficult instructions is money you waste by paying them to be at work without getting work done.

Current best practices call for spending about10% of a design project's budgeton usability. On average, this will more thandouble a website's desired quality metricsand slightly less than double an intranet's quality metrics. For software and physical products, the improvements are typically smaller — but still substantial — when you emphasize usability in the design process.

For internal design projects, think of doubling usability as cutting training budgets in half and doubling the number of transactions employees perform per hour. For external designs, think of doubling sales, doubling the number of registered users or customer leads, or doubling whatever other desired goal motivated your design project.

Howto Improve Usability

There are many methods for studying usability, but the most basic and useful isuser testing, which has 3 components:

  • Get hold of somerepresentative users, such as customers for an e-commerce site or employees for an intranet (in the latter case, they should work outside your department).
  • Ask the users to performrepresentative taskswith the design.
  • Observewhat the users do, where they succeed, and where they have difficulties with the user interface. Shut up and let the users do the talking.

It's important to test users individually and let them solve any problems on their own. If you help them or direct their attention to any particular part of the screen, you have contaminated the test results.

To identify a design's most important usability problems,testing 5 usersis typically enough. Rather than run a big, expensive study, it's a better use of resources to run many small tests and revise the design between each one so you can fix the usability flaws as you identify them.Iterative designis the best way to increase the quality of user experience. The more versions and interface ideas you test with users, the better.

User testing is different fromfocus groups, which are a poor way of evaluating design usability. Focus groups have a place in market research, but to evaluate interaction designs you must closely observe individual users as they perform tasks with the user interface.Listening to what people sayis misleading: you have to watch what they actually do.

Whento Work on Usability

Usability plays a role in each stage of the design process. The resulting need for multiple studies is one reason I recommend making individual studies fast and cheap. Here are the main steps:

  1. Before starting the new design,test the old designto identify the good parts that you should keep or emphasize, and the bad parts that give users trouble.
  2. Unless you're working on an intranet,test your competitors' designsto get cheap data on a range of alternative interfaces that have similar features to your own. (If you work on an intranet, read theintranet design annualto learn from other designs.)
  3. Conduct afield studyto see how users behave in their natural habitat.
  4. Makepaper prototypesof one or more new design ideas and test them. The less time you invest in these design ideas the better, because you'll need to change them all based on the test results.
  5. Refine the design ideas that test best throughmultiple iterations, gradually moving from low-fidelity prototyping to high-fidelity representations that run on the computer. Test each iteration.
  6. Inspect the design relative toestablished usability guidelineswhether from your own earlier studies or published research.
  7. Once you decide on and implement thefinal design, test it again. Subtle usability problems always creep in during implementation.

Don't defer user testing until you have a fully implemented design. If you do, it will be impossible to fix the vast majority of the critical usability problems that the test uncovers. Many of these problems are likely to be structural, and fixing them would require major re-architecting.

The only way to a high-quality user experience is to start user testing early in the design process and to keep testing every step of the way.

Whereto Test

If you run at leastone user study per week, it's worth building a dedicated usability laboratory. For most companies, however, it's fine to conduct tests in a conference room or an office — as long as you can close the door to keep out distractions. What matters is that you get hold of real users and sit with them while they use the design. A notepad is the only equipment you need.

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World's Best Headlines: BBC News

byJAKOB NIELSENon April 27, 2009

Topics:

  • Writing for the Web

Summary:Precise communication in a handful of words? The editors at BBC News achieve it every day, offering remarkable headline usability.

It's hard enough towrite for the Weband meet the guidelines forconcise, scannable, and objectivecontent. It'seven harderto write Web headlines, which must be:

  • short(because peopledon't read muchonline);
  • rich in information scent, clearly summarizing the target article;
  • front-loadedwith the most important keywords (because users oftenscan only the beginningof list items);
  • understandable out of context(because headlines often appear without articles, as in search engine results); and
  • predictable, so users know whether they'll like the full articlebeforethey click (because people don't return to sites that promise more than they deliver).

For several years, I've been very impressed with BBC News headlines, both on the main BBC homepage and on its dedicatednews page. Most sites routinely violate headline guidelines, but BBC editors consistently do an awesome job.

Concise and Informative

On a recent visit, the BBC list of headlines for "other top stories" read as follows:

  • Italy buries first quake victims
  • Romania blamed over Moldova riots
  • Ten arrested in UK anti-terrorism raids
  • Villagers hurt in West Bank clash
  • Mass Thai protest over leadership
  • Iran accuses journalist of spying

Around the world in 38 words.

The average headline consumed a mere5 wordsand34 characters. The amount of meaning they squeezed into this brief space is incredible: every word works hard for its living. I'm rarely that concise.

Each headline conveys the gist of the story on its own, without requiring you to click. Even better, each gives you a very good idea of what you'll get if you do click and lets you judge — with a high degree of confidence — whether you'll be interested in the full article. As a result, you won'twaste clicks. You'll click through to exactly those news items you want to read.

The site's top news headlines warrant a few additional keystrokes.

One breaking story, for example, had the following headline: "Suspected US missile strike kills four militants in tribal region in north-west Pakistan, officials say."

Readers would certainly know what happened, and would even get the general picture after the first 4 words.

To save space, the headline's writer might havedeferred the attributionto the unnamed "officials" to the article itself. That information isn't something people need to know at the headline-scanning stage; an exception would be if a famous person or controversial source had claimed responsibility for the missile strike, in which case the attribution might be a reason for users to click.

Also, using "4" might be better than using "four" given the general guideline toprefer numeralsfor online writing. But in this particular headline, the word works as well as the numeral because users aren't likely to be scanning the front page for data about the specific number of militants killed. To research such facts, people would typically start by searching for articles about the missile strike, and then scan one or two to get the numbers.

Roots of Success?

So why is the BBC so good when most others are so bad? Maybe it's in the BBC's blood: The news organization originated as a radio station, where word count is at a premium and you must communicate clearly to immediately grab listeners. In a spoken medium, each word is gone as soon as it's uttered, so convoluted exposition confuses even more than it does in print.

Ceefax (one of the longest-surviving videotext services) also helped instill conciseness in BBC's journalists until it was closed in 2012. Text on pre-HD televisions had horrible resolution and only allowed for a minute word count (somewhat likemobile).

Whatever the reason, BBC News headlines are almost always written to the highest Web usability standards. Visit the site daily for a week and try to apply some of the BBC editors' discipline to your own headlines.

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Top 10 Guidelines for Homepage Usability

byJAKOB NIELSENon May 12, 2002

Topics:

  • Web Usability

Summary:A company's homepage is its face to the world and the starting point for most user visits. Improving your homepage multiplies the entire website's business value, so following key guidelines for homepage usability is well worth the investment.

Homepages are themost valuable real estatein the world. Each year, companies and individuals funnel millions of dollars through a space that's not even a square foot in size. For good reason. A homepage's impact on a company’s bottom line is far greater than simple measures of e-commerce revenues: The homepage is your company'sface to the world. Increasingly, potential customers will look at your company's online presence before doing business with you — regardless of whether they plan to close the actual sale online. (Update: ourstudies of B2B usabilityfound that this is the predominant behavior of business users.)

The homepage is themost important page on most websites, and gets more page views than any other page. Of course, users don't always enter a website from the homepage. A website is like a house in which every window is also a door: People can follow links from search engines and other websites that reach deep inside your site. However, one of the first things these users do after arriving at a new site is go to the homepage.Deep linkingis very useful, but it doesn't give users the site overview a homepage offers — if the homepage design follows strong usability guidelines, that is.

Following are ten things you can do to increase the usability of your homepage and thus enhance your website's business value.

Make the Site's Purpose Clear: Explain Who You Are and What You Do

1. Include a One-Sentence Tagline

Start the page with ataglinethat summarizes what the site or company does, especially if you're new or less than famous. Even well-known companies presumably hope to attract new customers and should tell first-time visitors about the site's purpose. It is especially important to have a good tagline if your company's general marketing slogan is bland and fails to tell users what they'll gain from visiting the site.

2. Write a Window Title with Good Visibility in Search Engines and Bookmark Lists

Begin theTITLE tagwith the company name, followed by a brief description of the site. Don't start with words like "The" or "Welcome to" unless you want to be alphabetized under "T" or "W."

3. Group all Corporate Information in One Distinct Area

Finding out about the company is rarely a user's first task, but sometimes people do need details about who you are. Good corporate information is especially important if the site hopes to support recruiting,investor relations, orPR, but it can also serve to increase a new or lesser-known company'scredibility. An "About <company-name>" section is the best way to link users to more in-depth information than can be presented on the homepage. (See also my report with70 guidelines for the design of "about us" areas of corporate websites.)

Help Users Find What They Need

4. Emphasize the Site's Top High-Priority Tasks

Your homepage should offer users a clear starting point for the main one to four tasks they'll undertake when visiting your site.

5. Include a Search Input Box

Searchis an important part of any big website. When users want to search, they typically scan the homepage looking for"the little box where I can type,"so your search should be a box.[Make your search box at least 25 characters wide,]so it can accommodate multiple words without obscuring parts of the user's query.

(Update: Based on more recent findings, my recommendation is now to make the search box27 characters wide. This and other new guidelines are covered in my tutorial onFundamental Guidelines for Web Usabilityat the annualUsability Week conference.)

Reveal Site Content

6. Show Examples of Real Site Content

Don't just describe what lies beneath the homepage. Specifics beat abstractions, and you have good stuff. Show some of your best or most recent content.

7. Begin Link Names with the Most Important Keyword

Users scan down the page, trying to find the area that will serve their current goal.Links are the action itemson a homepage, and when you start each link with a relevant word, you make it easier for scanning eyes to differentiate it from other links on the page. A common violation of this guideline is to start all links with the company name, which adds little value and impairs users' ability to quickly find what they need.

8. Offer Easy Access to Recent Homepage Features

Users will often remember articles, products, or promotions that were featured prominently on the homepage, but they won't know how to find them once you move the features inside the site. To help users locate key items, keep a short list of recent features on the homepage, and supplement it with a link to a permanent archive of all other homepage features.

Use Visual Design to Enhance, not Define, Interaction Design

9. Don't Over-Format Critical Content, Such as Navigation Areas

You might think that important homepage items require elaborate illustrations, boxes, and colors. However, usersoften dismiss graphicsas ads, and focus on the parts of the homepage that look more likely to be useful.