Publish or Perish is a free, downloadable software program that uses Google Scholar data to help scholars track citations to their publications to demonstrate their impact for the purposes of tenure and promotion. In addition to basic descriptive statistics (such as number of publications, number of citations, number of citations per paper, number of citations per year, and so forth), it also calculates citation metrics, including the h-index and several variations on it, such as the g-index and the e-index.