Usability refers to five aspects of a person's use of an item. What are two of these aspects?

Usability is a key concept in design that refers to how easy and efficient it is for users to interact with a product, system, or service. It encompasses various aspects that contribute to the user experience. Two of these aspects are:

1. **Learnability**: This aspect of usability focuses on how easy it is for users to accomplish basic tasks the first time they encounter the design. A system with high learnability will be intuitive to new users, allowing them to quickly get up to speed and start using it with minimal instruction or training.

2. **Efficiency**: Once users have learned how to use a system, the next aspect of usability is how quickly they can perform tasks. Efficiency measures the speed at which experienced users can complete their tasks and achieve their goals. A system that enables users to perform actions rapidly and with a high level of productivity is considered to be efficient.

Other aspects of usability include memorability (how easy it is to remember how to use the system after not using it for a while), errors (how many errors users make, how severe these errors are, and how easily they can recover from them), and satisfaction (how pleasant the system is to use). These five aspects together help in evaluating the overall usability of a system.