Comprehensive review of the state and trends of the emerging carbon market as of June 2004, based on material provided by Natsource LLC and PointCarbon, and on direct interviews with market participants. The paper provides an overview of the main segments of this market, and how they inter-relate. It covers project-based transactions, which constitute, in volume terms, the biggest part of the current market, as well as providing a glimpse into the various GHG emissions allowances markets. The paper concludes with a discussion of the major trends emerging in the GHG market.