External memory refers to tools or aids that help us store and access information outside our own brain. Think of it like using a notepad to keep track of information you don't want to forget. This kind of memory allows us to save mental energy for other tasks and reduces the load on our working memory.

In the context of UX design, external memory might be any feature in a user interface that lets users save and retrieve information necessary for their tasks. For example, a comparison table on a shopping website acts as external memory. It helps users review different products side by side, keeping important details visible so they don’t have to remember everything about every item.