Designed to complement Essential Science IndicatorsSM in providing citation analyses and commentary for selected scientific research areas that have experienced notable recent advances or are of special current interest. Each topic is prefaced with a description of its relation to the main Essential Science Indicators rankings and the methodology used to assemble the data from the Essential Science Indicators database. The data presented for each topic include citation rankings for scientists, institutions, nations, and journals. Each topic also features interviews, essays, and profiles by prominent scientists in the area.