A worm is a specific type of virus that self replicates across many computers. It does not alter files but resides in the active memory and duplicates itself in each computer’s memory. Worm is invisible to the user and it operating system runs automatically. Worms can be noticed when their uncontrolled replication consumes the system’s resources causing the slowing down or halting of other tasks the users in undertaking.
Worm devices were first developed in the late 1970’s and since then they have been able to adapt to a number of different media. In the computer storage media the word WORM stands for “write once, read many”. Worms is just a data storage technology that allows information to be written to a diskette or CD a single time and then preventing the drive from erasing this data. The diskette or CD used was not rewritable as it intended to store the data that does not want to be erased accidentally. The devices of worm were long used by the organization such as government agencies or large enterprises for archival purposes.
Due to lack of standardization, worm disks have only been able to read by the drive on which it was written. The hardware and software incompatibility had also disadvantaged their marketplace acceptance. New optical media such as CD’s and DVD’s that can be recorded once and read unlimited of times are now considered worm’s devices, although there are arguments over it formatting that can be written in more than one session, known as “multi-session CDs”. Now days, gradually conventional worm devices are being replaced by CD-R and as new technology is emerging DVD-R and HD-ROM will soon replace both worm and CD-R devices.