What is flash?
Flash is a type of non‑volatile electronic storage that keeps its data even when the power is turned off. It’s made of tiny memory cells that can be electrically erased and rewritten, which is why you see it in USB sticks, memory cards, solid‑state drives (SSDs) and many other gadgets.
Let's break it down
Flash memory is built from millions of tiny cells arranged in a grid. There are two main families: NAND (used for high‑capacity storage like SSDs and cards) and NOR (used for code storage where fast reads are needed). Data is stored as electric charges; writing means adding charge, erasing means removing it. Because you can’t change a single cell directly, data is written and erased in blocks.
Why does it matter?
Because flash doesn’t need moving parts, it’s fast, lightweight, and can survive drops and vibrations. It also uses very little power, which makes batteries last longer. These traits let modern devices be portable, silent, and reliable.
Where is it used?
- Smartphones and tablets (internal storage)
- Digital cameras and camcorders (memory cards)
- USB flash drives and external SSDs (portable storage)
- Laptops and desktops (SSDs)
- Embedded systems like routers, IoT devices, and automotive infotainment
Good things about it
- High read speed, decent write speed
- No mechanical parts → resistant to shock and wear
- Very low power consumption
- Small physical size, allowing slim devices
- Prices have dropped dramatically, making large capacities affordable
Not-so-good things
- Limited write/erase cycles (each cell can only be rewritten a finite number of times)
- Data can degrade over many years if not refreshed (especially in cold storage)
- Writing is slower than reading because it must erase whole blocks first
- Requires complex wear‑leveling algorithms to spread wear evenly across the chip
- If the controller fails, the whole drive can become unreadable, making data recovery difficult.