  The 2021-22 High-Energy Physics Community Planning Exercise (a.k.a.
``Snowmass 2021'') was organized by the Division of Particles and Fields of the
American Physical Society. Snowmass 2021 was a scientific study that provided
an opportunity for the entire U.S. particle physics community, along with its
international partners, to identify the most important scientific questions in
High Energy Physics for the following decade, with an eye to the decade after
that, and the experiments, facilities, infrastructure, and R&D needed to pursue
them. This Snowmass summary report synthesizes the lessons learned and the main
conclusions of the Community Planning Exercise as a whole and presents a
community-informed synopsis of U.S. particle physics at the beginning of 2023.
This document, along with the Snowmass reports from the various subfields, will
provide input to the 2023 Particle Physics Project Prioritization Panel (P5)
subpanel of the U.S. High-Energy Physics Advisory Panel (HEPAP), and will help
to guide and inform the activity of the U.S. particle physics community during
the next decade and beyond.
