When it comes to web design, usability is a measure of the ease with which site visitors can use the website to archive a particular goal. It is a measure for the website’s efficiency and elegance. In human-computer interaction and computer science, usability studies the elegance and clarity with which the interaction with a computer program or a web site is designed.

When evaluating the design and usability of a website, one must consider the following:

Know the target audience. The designer is not the target audience.

When designing a website it is important to specifically cater for the needs of the intended target audience. What are their needs, expectations & goals? What does a potential site visitor want to achieve on the website? It is important as a designer to be able to put himself into the shoes of the client & their customers. How does the client want to maintain the website and how can you enable the client to cater for their customers? The designer has to shift  his perspective so that his view is similar to the user’s standpoint. Understanding the abilities & needs of the client is a major key factor in this regard.

Things that look the same should act the same.

Usability heavily relies on the user being able to predict the consequences of his actions. Website elements such as buttons and links that have a similar appearance should trigger similar events that aid the user to achieve their goals. Inconsistent behaviors of similar looking elements on the website cause confusion, disorientation & frustration. In a similar manner it should be achieved that things that look different act differently.

The information for the decision needs to be there when the decision is made.

To create interactivity the website visitor has to be able to make choices – where he wants to navigate, which content he wants to explore, which particular action of an array of possibilities he wants to follow. It is very beneficial for the end user to be provided with sufficient information that support making those decisions. Helpful information can be supplied by explanatory hints, examples & demonstrations.

Error messages should actually mean something to the user and tell the user how to fix the problem.

If a site visitor encounters an error message that says something along the lines of “error 231″  or “an unknown error occurred” it leaves him with no information what actually caused the error or how to fix it. It is recommended to provide informative error messages that explain why the error was caused and also offer a solution how to fix it. An example for an error caused by an E-mail form field validation could be: “you have entered an incorrect E-mail address, it should be in the format someone@host.com”.

Every action should have a reaction.

A website often has the functionality of a user interface. When site visitors are provided with interactive elements such as menus, buttons or form fields they should also be supplied with feedback to their actions. A click on a navigational element should lead the user to the desired content.  Especially in the event of content loading is is good practice to let the user know that the loading is in progress and how long it will take to view the desired information.

Everyone makes mistakes, so every mistake should be fixable.

A well designed website caters for every possible input from the user. Even if the user makes a mistake there should be the possibility for errors to be corrected.

Don’t overload the user’s buffers.

As websites are a medium to be displayed on computers, mobile phones & other devices there is a need for technical compliance & a well thought through programming practice that uses as little hardware resources as possible. It is important not to use up too much of the user’s RAM as it might cause slow performance or even a system crash.

Consistency, consistency, consistency.

A consistent design is one that does not contain any contradiction. Consistency should be applied to the structure of a website as well as the presentation of content. A  layout that conforms to consistency assists a site visitor to identify which pages belong to a certain website which improves overall user-friendliness tremendously.

Minimize the need for a mighty memory.

Information should be provided to the end user as it is needed. A web designer should not expect the user to remember large amounts of information as it puts a strain on his cognitive work load. The smaller the load is that has to be memorized the more thinking capacity is available for engaging the website. In this regard it is a good idea to always let the user know where he is within a website. This provides good orientation & reduces the amount of information to be memorized.

Keep it simple, stupid (KISS Principle)

The KISS principle postulates simplicity. If there is a variety of solutions for a specific problem in a design the simplest alternative is most of the time the best. A design that is simple is easy to understand, often provides a good overview of choices and keep the cognitive load for the user low. With experience as a designer you will find that solving problems in simple way adds elegance to your creation.

The more you do something, the easier it should be to do.

In advanced dynamic web applications it is possible to recognize  usage pattern. It is good practice to provide the option to automate interaction processes according to these patterns. Advanced e-commerce websites for example such as amazon.com recognize shopping preferences and target offers to cater specifically for the user making the shopping process easier & quicker. Another example of amazon.com’s  streamlining of the user experience is the patented one-click checkout. Based on previous purchases and the collected billing & delivery information a customer can order a product with a single click.

Eliminate unnecessary decisions and illuminate the rest.

When decisions are needed from the site visitor it is desirable to limit the choices to the necessary amount.  When the customer for example chooses his country to be Australia & then subsequently has to choose his state it is a good idea to limit the states to choose from to the states located in Australia. This process simplifies the interaction & leaves a smaller margin for error. If certain options are grayed out & others are highlighted it provides the user with a chance to understand the constellation of a set of choices that go together.

The best journey is the one with fewest steps. Shorten the distance between the user and the goal.

Every site visitor visits a website with a certain expectation & a certain goal. If the web designer has the chance to arrange the structure and content of a site is such manner that user can reach their goal in as few clicks as possible then he should do so. Short paths to reaching desired goals keep customers motivated, satisfied & it saves time. There is also a smaller chance of a site visitor leaving your site & a bigger chance of users returning to your online presence.