# Usability

Usability is a topic that is often used interchangeably with user experience (UX), but they are not the same thing. Usability is a subset of UX, focusing specifically on the ease of use and effectiveness of a product, i.e., it is the ease with which users can learn and use a product to achieve their goals. Usability is a key factor in determining the success of a product, as it directly impacts user satisfaction, productivity, and overall experience. A system that is difficult to use or understand can lead to frustration, errors, and ultimately, abandonment by users.

Closely coupled with usability and UX is the concept of [accessibility](./accessibility.md).

## Characteristics

The main three characteristics of usability are:
- Effectiveness: Users should be able to accomplish their goals with the product.
- Efficiency: Users should be able to perform tasks quickly and with minimal effort. Oftentimes this is measured in terms of time on task or number of clicks.
- Satisfaction: Users should find the product enjoyable and satisfying to use.

Additional characteristics include:
- Learnability: Users should be able to easily and quickly learn how to use the product. In other words, the system should be intuitive and require minimal training.
- Memorability: Users should be able to remember how to use the product after a period of not using it.
- Errors: Users should encounter a minimal number of errors when completing a task, and recover easily from any errors that do occur.
- Simplicity: The system should be simple and straightforward to use, with minimal complexity and cognitive load.
- Comprehensibility: Users should be able to understand the system and its features easily, with clear instructions and feedback.


## Implementations

One way of implementing usability in a user interface is by basing your design decisions on usability testing results. Usability testing's goal is to identify any usability issues, gather feedback, and make improvements to the product. It can be conducted at various stages of the design and development process, from wireframes and prototypes to the final product.

These evaluations can collect two key metrics: **quantitative data** and **qualitative data**. Quantitative data can be collected through observing the facts of what actually happened. Qualitative data can be collected through interviews, observations, and other methods that provide insights into user behavior and preferences. There are several methods for conducting usability testing, including, but not limited to:
- Focus groups
- Wireframes
- Prototyping
- Surveys/Questionnaires
- Interviews
- [Think-aloud protocol](https://en.wikipedia.org/wiki/Think_aloud_protocol)

## Examples

One example of usability in action is the design of a website. A website that is easy to navigate, with clear labels, intuitive menus, and a logical flow of information, is more likely to be successful than one that is cluttered, confusing, and difficult to use. The latter website is likely to have a low rate of user engagement, high [bounce rates](https://backlinko.com/hub/seo/bounce-rate), and low conversion rates, as users will quickly become frustrated and abandon the site.

## Resources

- [GeeksForGeeks: What is Usability?](https://www.geeksforgeeks.org/what-is-usability/)
- [Usability.gov](https://www.usability.gov/)
- [Human-computer Interaction (HCI)](https://en.wikipedia.org/wiki/Human%E2%80%93computer_interaction)
- [Jakob Nielsen's 10 Usability Heuristics for User Interface Design](https://www.nngroup.com/articles/ten-usability-heuristics/)

