Emphemeral and immutable
When storing data, most data have a lifecycle - it created, managed and eventually deleted through operation of the application or script that use it. There are however to kinds of data storage which is slightly different, which developers should know about as they may be nice patterns to know and use when applicable.
Emphemeral data
The first data storage is emphemeral data. This kind of data will eventually automatically be deleted. In most cases the data is stored shortly - an hour, a day or a week - but there isn’t any fixed rule which define when the data disappear - just that it does by itself without any explicit cleanup or pruning from the developer (or user).