The American Library Association provides three definitions of digital preservation:
Short Definition
"Digital preservation combines policies, strategies and actions that ensure access to digital content over time."
Medium Definition
"Digital preservation combines policies, strategies and actions to ensure access to content that is born digital or converted to digital form regardless of the challenges of file corruption, media failure and technological change. The goal of digital preservation is the most accurate rendering possible of authenticated content over time."
Long Definition
"Digital preservation combines policies, strategies and actions to ensure the most accurate rendering possible of authenticated content over time, regardless of the challenges of file corruption, media failure and technological change. Digital preservation applies to content that is born digital or converted to digital form.