A Secure Digital (SD) card is a small, removable memory card that uses flash memory to store digital data. SD card became so popular to iPod modders because of the following advantages over the traditional Hard Disk Drive (HDD):
- It has no moving parts so it is less prone to damage from drops or shakes;
- It is smaller and lighter;
- It provides faster data access and boot times compared to a spinning HDD;
- SD card uses less power which helps improve the iPod battery life;
- No spinning disk means silent operation which enhances user experience;
- SD card is more tolerant of temperature changes compared to hard disk drives.