Last year we launched Volume 1 of the Reviews in Fluorescence series. The volume was well-received by the fluorescence community, with many e-mails and letters providing valuable feedback, we subsequently thank you all for your continued support. After the volume was published we were most pleased to learn that the volume is to be citable and indexed, appearing on the ISI database. Subsequently, as well as the series having an impact number in due course, individual chapters will appear on the database and be both citable and keyword searchable. We feel that this will be a powerful resource to both authors and readers, further disseminating leading-edge fluorescence based material. Our intention with this new series is to both disseminate and archive the most recent developments in both past and emerging fluorescence based disciplines. While all chapters are invited, we welcome and indeed encourage the fluorescence community to suggest areas of interest that they feel need to be covered by the series. In this new volume. Reviews in Fluorescence 2005, Volume 2, we have invited reviews in areas such as: Multi-dimensional Time-correlated Single Photon Counting; Fluorescence Correlation Spectroscopy; RNA folding; Lanthanide Probes and Fluorescent Biosensors to name but just a few. We hope you find this volume a useful resource and we look forward to receiving any suggestions you may have. Finally we would like to thank the authors for their timely articles, Caroleann Aitken for the fi-ont cover design, Kadir Asian for typesetting and Mary Rosenfeld for administrative support.