Digital preservation is a process consisting of managed activities and a supporting infrastructure that ensure digital objects are accessible, usable and authentic, for as far into the future as necessary.
To achieve this goal, digital preservation should be viewed as having a logical and a physical component. Physical digital preservation means that the bit streams (1s and 0s) stored on physical media (fixed or removable) will be “kept alive” by periodically transferring the bit streams to new media. Logical digital preservation is based on the fact that bit streams can only become intelligible and usable to humans and other computational means through rendering by software that decodes the bit streams and interprets the formats in which they are embedded.
Source: Long Term Digital Preservation