An Alternate Site is a site held in readiness for use during a business continuity event to maintain an organisation’s business continuity. An alternate site may be for use during/following an invocation of business or disaster recovery plans to continue urgent and important activities of an organization.
The term applies equally to work space or technology requirements. Organisations may have more than one alternate site. In some cases, an alternate site may involve facilities that are used for normal day-to-day operations but which are able to accommodate additional business functions when a primary location becomes inoperable. Examples of alternate sites include relocation and disaster recovery sites, whether managed directly or maintained by a third party for an organisation’s exclusive use or for use by multiple organisations. 
- BCBS, High-level principles for business continuity, August 2006