The experts have put a lot of effort into clarity in this area and a good working definition for the sake of this guide is:

“The series of managed activities necessary to ensure continued access to digital materials for as long as necessary.”

This definition comes from the Digital Preservation Coalition (DPC) Definitions and Concepts list and I feel it works because it is clear and specific.

Let’s look at it a little closer:

• Managed – Digital preservation is a managerial problem. All activities (the planning, resource allocation, use of technologies, etc.) need to have been thought about and take place for a reason. The term managed stresses the need for a policy.
• Activities – The policy needs to filter down to a list of processes: tasks that can take place at specified times and in specified ways.
• Necessary – We are looking at what needs to be done. In your policy you will have looked at how long you want to preserve the objects for. Necessary talks about the activities needed to achieve a specified level of preservation. there may be other useful activities but we want to look at the most essential ones here.
• Continued Access – Access is the key here. Most objects in the public sphere are preserved to enable access and retrieval. How long this access is needed will have been discussed and should be defined in your policy.
• Digital Materials – Digital materials, digital objects, call them what you will. This is the stuff you are preserving. Different objects require different processes.

Other useful definitions are available from DigitalPreservationEurope (DPE), the Digital Curation Center (DCC) , the Digital Preservation of ALCTS Preservation and Reformatting Section (Working Group on Defining Digital Preservation) and Wikipedia. Note that digital curation tends to refer more to science/reserach data.

Many organisations choose to quantify their definition of digital preservation by 3 terms of preservation:

• Long-term preservation – Continued access to digital materials, or at least to the information contained in them, indefinitely.
• Medium-term preservation – Continued access to digital materials beyond changes in technology for a defined period of time but not indefinitely.
• Short-term preservation – Access to digital materials either for a defined period of time while use is predicted but which does not extend beyond the foreseeable future and/or until it becomes inaccessible because of changes in technology.

For JISC projects it will normally be require that digital objects are preserved for the medium-term or the long-term.

A really useful slideshow introduction to digital preservation was written by Michael Day, UKOLN and is available on Slideshare.