Most applications are stateful. Stateful is when streaming services remember where you left off in a movie even if you switch devices, or mobile applications store users’ preferences or recently opened files. For application-level cases, it’s the ability to recover from a session interruption, putting the users back to the place they left off, without loss of data.
We come from a stateful world. Stateful applications remember things about states, which is durable across sessions. The state data is stored within some nonvolatile mechanism, such as physical storage, including databases.
