More than one thousand photochemistry papers were published in the most cited twenty-four scientific journals in 2007. With nanosecond, picosecond, and femtosecond laser techniques widely applied, detection of reactive intermediates, products of chemical bond dissociation, isomerizations, rearrangements, as well as the initial results of intramolecular energy or electron transfer, become facile. Complex photoluminescence, DNA sequence-directed structure and dynamics studies, photopolymerization, and photocatalysis remain important topics. Because optical single-molecule detection, photoprobes, and photosensors have been increasingly applied in the chemical and biological sciences, these have received specific attention. The photochemistry of nanoparticles and nanostructures has also attracted much attention. Optical devices, photoswitches, and two-photon/multiphoton chemistry have been widely investigated. In this review, we briefly summarize major progress in the photochemical sciences and selected applications are discussed.