# SSD

> Storage with no moving parts: where your files live when the power is off.

- Level: Basic
- Topics: Hardware
- URL: https://tidbit.legios.com.ar/ssd/
- In Spanish: [SSD](https://tidbit.legios.com.ar/es/ssd/)

An **SSD** (Solid-State Drive) is the storage in almost every modern laptop, phone and server: the place where files, programs and the operating system stay saved when the power is off. It stores data in flash memory chips, the same technology as a USB stick, and it has no moving parts. The older alternative, the **hard disk drive** (HDD), spins magnetic platters and reads them with a moving arm.

The difference you feel is speed. An SSD finds any file in a fraction of a millisecond; a hard disk has to physically move its arm, which takes several milliseconds. That is why a computer with an SSD boots in seconds and opens apps instantly, and why replacing an old laptop's hard disk with an SSD was for years the single best upgrade. SSDs are also silent, lighter and survive drops.

Hard disks have not disappeared: per gigabyte they are still much cheaper, so data centers use them for backups and the bulk of cloud storage like Amazon S3, with SSDs in front for the hot, frequently accessed part. Flash cells also wear out after many writes, though modern drives manage this well enough that a normal user never notices.

SSD versus RAM, since people confuse them: RAM is the fast working memory that empties when you shut down; the SSD is the persistent storage that keeps your files. More RAM makes multitasking smoother; a bigger SSD lets you keep more files.

## An analogy

A hard disk is a record player: the needle has to travel to the right groove. An SSD is a book with tabs: you open straight to any page, with nothing to move.

## Keep in mind

- Persistent storage made of flash chips; no moving parts, very fast access.
- Replaced hard disks in laptops and phones; hard disks remain for cheap bulk storage.
- Connects through SATA (older, slower) or NVMe over PCIe (newer, much faster).
- Not the same as RAM: the SSD keeps data when powered off, RAM does not.

## Go deeper

- [Solid-state drive on Wikipedia](https://en.wikipedia.org/wiki/Solid-state_drive)
- [Flash memory on Wikipedia](https://en.wikipedia.org/wiki/Flash_memory)

## Related terms

- [Server](https://tidbit.legios.com.ar/server/): A computer whose job is to answer requests from other computers, all day, every day.
- [Operating system](https://tidbit.legios.com.ar/operating-system/): The base software that runs a device and lets every app share its hardware.
- [Chip](https://tidbit.legios.com.ar/semiconductor-chip/): A sliver of silicon carrying billions of tiny switches that compute and remember.
- [USB](https://tidbit.legios.com.ar/usb/): The standard plug for connecting and charging almost everything.
- [Hard disk drive](https://tidbit.legios.com.ar/hard-disk-drive/): Storage that keeps data on spinning magnetic platters: slower than an SSD, but cheap.
- [Data center](https://tidbit.legios.com.ar/data-center/): A building full of servers where the internet, the cloud and AI actually run.
- [Backup](https://tidbit.legios.com.ar/backup/): A separate copy of your data, kept so you can get it back when the original is lost.
- [Cloud computing](https://tidbit.legios.com.ar/cloud-computing/): Renting computers over the internet instead of buying your own.