These devices are used to store the data permanent for future use. For example – Hard disk, CD, Pen drive, SD card
Hard disk
Hard disk are flat circular plates made of aluminum or glass and coated with a magnetic material. Hard disks for personal computers can store terabytes information. Data are stored on their surfaces in concentric tracks.
CD
A compact disc is a portable storage medium that can be used to record, store and play back audio, video and other data in digital form.
A standard compact disc measures 4.7 inches, or 120 millimetres, across, is 1.2mm thick, weighs between 15 grams and 20 grams, and has a capacity of 80 minutes of audio, or 650 megabytes to 700MB of data.
Pen drive
A USB flash drive is a data storage device that includes flash memory with an integrated USB interface. It is typically removable, rewritable and much smaller than an optical disc.
SD card
Secure digital, official abbreviated as SD, is a proprietary non volatile memory card format developed by the SD Association for use in portable devices. Secure digital from top to bottom: SD, miniSD, microSD. Media type.