The Dark Energy Science Collaboration (DESC) is the international science collaboration that is preparing to make high precision and high accuracy measurements of fundamental cosmological parameters using data from the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). The LSST DESC will carry out cosmological analysis using at least five dark energy probes: weak and strong gravitational lensing, large-scale structure, galaxy clusters, and supernovae. Preparing for this ambitious undertaking requires intensive efforts to develop, implement, and improve analysis software that we test by producing, processing, and analyzing image simulations and precursor survey data. In this talk I provide an overview of DESC including information about publicly available software and simulated datasets, especially highlighting a release of catalogs based on simulated LSST images produced as part of our Data Challenge 2 (DC2). This talk serves as context for subsequent talks in this special session in which DESC members describe recent science and technical results from the aforementioned efforts.