Digital devices are really amazing machines. They are built around a micro-processor that is capable of carrying out millions of calculations a second. The processor is called ?micro? because it is small enough to fit inside the palm of your hand. It is fixed over a motherboard which in turn has wires running to all parts of the system such as input and output devices and the power supply.

The other important component of a computer or laptop is the hard disk. This is the primary storage device where all data inputted by the user along with software programmes and operating system reside. The major benefit of hard disks is that they give random access to data stored anywhere on their recording surface. They are also quite reliable, easily lasting through five or six years of constant use.

However, the disks are quite complex machines with many delicate components. They are bound to crash sooner or later due to hardware or software errors. When this happens, all your data gets lost, leading to much frustration and financial damage. That is why it is a good idea to take a backup of all your important data regularly.

There is a wide range of data backup media that can be used for the purpose.

Called CDs for short, these disks are the backup media of choice worldwide. CDs are small platters made of thin but very durable plastic with a hole in the centre. The disks hold data in a single circular groove that starts from the centre and goes around it again and again, working its way outward toward the edge.

This groove is so tightly packed on the disk that if unwound, it would stretch to a distance of 5 kms! That is why these disks have a huge data-storage capacity compared to their size. Each can hold up to 700 MB of data. CDs come in two versions ? Write Once (CD-R) and Re-writable (CD-RW). The latter can be written over hundreds of times and are ideal candidates for taking small backups.

Popularly called DVDs, these disks are the more powerful version of CDs. They work on the same optical technology as the latter and are exactly the same size but there is a huge difference in data-holding capacity. Compared to a mere 700 MB of data that a CD can hold, a DVD has the capacity of a whopping 4.6 GB of data that is enough to accommodate even full-length movies.

Thus, a single DVD can record more data than seven CDs put together. What is more, double-layered DVDs can hold up to 8 GB of data! This is more than sufficient capacity for the data-backup needs of most individuals and small businesses.

Also called memory sticks, thumb drives, pen drives or key-chain drives, these storage devices are the latest technology on the block. They use Flash memory to store data through the USB port of a computer or laptop. USB drives have many benefits, such as small size and fast data-transfer speeds. Unlike hard disk drives, they have no moving parts and are immune to strong magnetic fields. These drives are clearly the technology that is going to dominate the future of the data-storage devices.

These are stand-alone hard disks that have been made rugged and portable. They have a huge capacity, ranging from 80 GB to an amazing 500 GB. Portable disks are generally used by companies with large data storage needs. Because of their huge data-holding capacity, they can hold mirror images of a number of hard disks and preserve all their data.

There is currently no other storage device available that offers such a capability with random data access. Though portable hard drives cost about double the price of standard hard drives fixed inside computers, they are well worth the money. They last for about 6 to 10 years of constant use, helping you carry on with work without any problem even if the entire hard disk of your computer dies on you.

Tape drives, as the name suggests, are based on the very old but tried-and-tested technology of magnetic tape. They are the preferred backup media for many companies because no other storage device can match them in reliability as well as cost per MB of data stored.

Tape drives use small plastic cartridges with a capacity of up to 80 or 120 GB. The data is stored over a long length of magnetic tape that is wound around a couple of spools inside the cartridge. Though these drives provide only sequential access to the stored data, they are still highly popular for taking backups because of their low cost, long life and dependability.