There are many ways to store data. For example, there are presently three types of CD drives available, and five kinds of DVD drives. The chart below lists the most common types of storage available today. Magnetic storage media can be read and written many times, but some optical media are read-only, and some are write-once (but they can be read many times).
| Name
| Type
| Capacity
| Writability
|
| High-density floppy disk
| Magnetic
| 1.44 MB
| Unlimited
|
| SecureDigital card
| Solid state
| 128 MB - 32 GB
| Many
|
| CompactFlash card
| Solid state
| 512 MB - 100 GB
| Many
|
| Super floppy
| Magnetic
| 120 or 240 MB
| Unlimited
|
| USB storage device (thumb drive)
| Solid state
| 4 GB or 8 GB
| Many
|
| CompactFlash form factor—Microdrive
| Magnetic
| 340 MB to 8 GB
| Unlimited
|
| Iomega Zip disk
| Magnetic
| 100, 250, or 750 MB
| Unlimited
|
| CD-ROM
| Optical
| 900 MB
| Read only
|
| CD-R
| Optical
| 650 or 700 MB
| Write once
|
| CD-RW
| Optical
| 650 or 700 MB
| Many
|
| DVD+/-R
| Optical
| 4.7 GB
| Write once
|
| DVD+/-RW
| Optical
| 4.7 GB
| Many
|
| DVD+R DL (dual layer)
| Optical
| 8.5 GB
| Write once
|
| DVD-ROM (SLSS)
| Optical
| 4.7 GB
| Read only
|
| DVD-ROM (DLSS or SLDS)
| Optical
| 8.5 GB
| Read only
|
| DVD-ROM (DLDS)
| Optical
| 18.8 GB
| Read only
|
| Internal hard disk drive
| Magnetic
| 160 GB to 1TB or more
| Unlimited
|
| External hard disk drive
| Magnetic
| 20 GB to 1 TB or more
| Unlimited
|
Table 1 Comparison of storages
