This document provides background information on the topic of reforming UN peacekeeping operations. It discusses the evolution and expansion of peacekeeping since 1948. It notes the increasing complexity of modern peacekeeping missions and issues that may need reform, such as improving response times and addressing misconduct. The UN has undertaken various reviews to improve peacekeeping, including the 2000 Brahimi Report, but further reforms are still seen as needed. Developing nations contribute most peacekeeping troops while developed nations provide most funding.