Use this tag when dealing with data that is being cached.

A cache (pronounced CASH or CAYSH depending on your English dialect) is a place to store something temporarily in a computing environment.

In computing, active data is often cached to shorten data access times, reduce latency and improve input/output (I/O). Because almost all application workload is dependent upon I/O operations, caching is used to improve application performance. (source)

Caching is like short-term memory and can be responsible for unexpected data being displayed or data not being "forgotten" after the data has been removed from its original location.