Cognitive load is the mental effort required to process and understand new information. It is an important factor in the user experience of websites and apps, as it directly affects how easily users can understand and use the product.

When using a website or app, the user's brain is constantly processing information and making decisions. This requires the use of working memory, which is a limited capacity part of short-term memory. Working memory is responsible for holding and manipulating the information needed to reason and make decisions.

If the cognitive load on a user becomes too high, it can lead to confusion, frustration, and ultimately, abandonment of the product. This is because their working memory becomes overwhelmed and unable to effectively process the information it is being presented with.

Designers and developers can help to reduce cognitive load by simplifying the user interface, providing clear and concise instructions, and minimizing the amount of information that needs to be processed at any one time. By reducing cognitive load, designers and developers can create a better user experience and increase the chances of user engagement and retention.