There is a quiet tension at the heart of handling data: regulations often require you to keep certain records for years, while keeping data longer than necessary is itself a growing liability. A data retention and disposal policy is how a system threads that needle deliberately rather than by accident.
Every piece of data you retain is data that can be breached, subpoenaed, or misused. The instinct to keep everything indefinitely, because storage is cheap, ignores that each record is also a liability. Data minimization, keeping only what you need for only as long as you need it, is now a recognized security and privacy principle, not just good housekeeping. The safest data is the data you no longer hold.
A retention policy specifies, for each category of data, how long it is kept and why, tied to the legal, regulatory, or business reason for keeping it. Records required by regulation are held for the mandated period; data with no ongoing purpose is scheduled for disposal. The policy turns retention from a default of forever into a deliberate decision per data type.
Disposal is the other half. Deleting data must be genuine and secure, so it cannot be reconstructed, and it must extend to backups and copies, which are easy to forget. A policy that defines retention but never actually disposes leaves the liability intact. Done right, retention and disposal shrink both regulatory risk and breach exposure at once.
Keep what you must, dispose of the rest.
This is general educational information, not specific security, compliance, or legal advice for your systems.