The word error entails different meanings and usages relative to how it is conceptually applied. The concrete meaning of the Latin word "error" is "wandering" or "straying". Unlike an illusion, an error or a mistake can sometimes be dispelled through knowledge (knowing that one is looking at a mirage and not at real water does not make the mirage disappear). For example, a person who uses too much of an ingredient in a recipe and has a failed product can learn the right amount to use and avoid repeating the mistake. However, some errors can occur even when individuals have the required knowledge to perform a task correctly. Examples include forgetting to collect change after buying chocolate from a vending machine, forgetting the original document after making photocopies, and forgetting to turn the gas off after cooking a meal. Some errors occur when an individual is distracted by something else.