The phrase change review board (also known by the acronym CCB) refers to any group of individuals within a project team or project group who are responsible for making the ultimate decision as to when and if any particular changes are to be made in regards to work products or schedule events. The process in which the Change Control Board determines when and if a series of changes should be made is two fold. First, the Change Control Board needs to review and study the impact of the proposed changes on the items in question, and then, after making that evaluation, the Change Control Board can then either approve the changes, reject the changes, or, in some cases, request more information or postpone the decision pending some other occurrences to take place that would factor into their ultimate choice. Significant changes that will in fact affect baselines are almost always put through the CCB for approval.
This term is defined in the 3rd and the 4th edition of the PMBOK.