ISO 27001 enhanced the content of BS7799-2 and harmonized it with other standards. A scheme has been introduced by various certification bodies for conversion from BS7799 certification to ISO27001 certification.
The objective of the standard itself is to "provide a model for establishing, implementing, operating, monitoring, reviewing, maintaining, and improving an Information Security Management System". Regarding its adoption, this should be a strategic decision. Further, "The design and implementation of an organization's ISMS is influenced by their needs and objectives, security requirements, the process employed and the size and structure of the organization".
The standard defines its 'process approach' as "The application of a system of processes within an organization, together with the identification and interactions of these processes, and their management". It employs the PDCA, Plan-Do-Check-Act model to structure the processes, and reflects the principles set out in the OECG guidelines (see oecd.org).
For further information, see our page explaining the ISO27001 Certification Process