[Derrick Adams]

Data is kept in three broad tiers. Primary storage is volatile memory (RAM). It holds the working data and code the CPU needs right now. It is fast, but everything is lost when power is off. Secondary storage is persistent media such as SSDs and HDDs. This is where operating systems, apps, and user files live day-to-day, SSDs give speed, while HDDs offer larger, cheaper capacity. archival storage is built for long retention and low cost—think magnetic tape or optical media. These “cold” copies are slow to access, but ideal for compliance and disaster recovery.
Organizations also use external USB drives for quick transfers, and networked storage (NAS for file shares, SAN for block storage) to centralize data for servers. Cloud storage adds elasticity: object storage for backups and media, block storage for virtual machines, and managed file shares for lift-and-shift workloads.