Flash memory cards and SSD technology come in many form factors and are used in a wide array of devices, making it a challenge to sort out the best options. This ebook offers an in-depth look at the most important aspects of flash storage, including speed classes, form factors, and use cases.

From the ebook:

Flash memory is an electronic, nonvolatile data storage medium that is erased and reprogrammed electrically. It is the basis of a variety of storage products for differing use cases, form factors, and speed or performance requirements. Flash memory is the underpinning of modern consumer technology—it is used to store photos taken with digital cameras and is found in smartphones, tablets, game consoles, and solid-state drives used in computers. This overview offers the key information you need to know about the topic.
What is flash storage?

Flash memory is an electronic, solid-state storage medium developed by Fujio Masuoka while working at Toshiba, circa 1980. Masuoka first publicly demonstrated the invention in 1987, with Intel producing the first commercial flash chip in 1988.

Masuoka’s invention covers two related types of nonvolatile memory: NOR and NAND. NOR flash takes longer to write or erase but provides byte-level random access, making it a suitable replacement for read-only memory (ROM) chips. NAND flash provides faster write and erase times, as well as more dense storage capabilities. NAND flash is written and read at a block level, making it unsuitable for embedded use cases that require byte-level access.

Generally, NOR flash is restricted to mission-critical applications and embedded use cases, such as the firmware of a computer or an embedded electronic device. Flash memory cards and solid-state drives (SSDs) use NAND flash for mass storage.