💾 Where Does Your Data Live?

Storage Technology Comparator

Your photos, music, games and homework all need to be stored somewhere. But hard drives, SSDs, USBs, CDs and DVDs all work completely differently. See how — and why it matters.

CS GCSE §1.1.2 CS A-Level Unit 1 DigiTech GCSE §1.1.1

🤔 Three types of storage

All computer storage falls into three categories based on how it physically stores data:

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Magnetic

Tiny magnets flipped north/south to store 1s and 0s

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Optical

Laser burns tiny pits into a disc — pits and lands represent 1s and 0s

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Solid State

Electrical charges trapped in tiny cells — no moving parts

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Compare storage devices

Click a device to see its stats. Compare them side by side.

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How does each type work?

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Magnetic

A spinning platter (disc) coated in magnetic material. A tiny read/write head moves across the surface, flipping magnetic particles to store 1s and 0s.

Like: A record player — but instead of playing music from grooves, it reads data from magnetic patterns on a spinning disc.

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Optical

A laser burns tiny pits (dips) into the surface of a disc. A different laser reads the disc — pits scatter the light (0), flat areas (lands) reflect it (1).

Like: Reading Braille — the bumps and flat parts on the surface carry the message.

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Solid State

No moving parts. Data stored as electrical charges in millions of tiny transistors (called NAND flash cells). Charge = 1, no charge = 0.

Like: A huge grid of light switches — each one is either ON (1) or OFF (0). Billions of switches = billions of bits.

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Exam Terms

Term	Meaning	Example
Volatile	Loses data when power is turned off	RAM — that's why unsaved work disappears in a power cut!
Non-volatile	Keeps data without power	SSD, HDD, USB — your files survive a shutdown
Capacity	How much data it can hold	Measured in GB or TB (1 TB = 1,000 GB)
Access speed	How fast data can be read/written	SSD: ~500 MB/s, HDD: ~100 MB/s
Durability	How resistant to physical damage	SSD (no moving parts) > HDD (spinning disc can break)
Portability	How easy to carry around	USB stick (pocket) vs HDD (bulky) vs cloud (anywhere with WiFi)

📝 Exam tip: You'll often be asked to recommend storage for a scenario. Key question: "Do they need speed (SSD), capacity (HDD), portability (USB), or cheapness (optical)?" Always justify with at least 2 reasons.