  The Compact Linear Collider (CLIC) is a multi-TeV high-luminosity linear
e$^+$e$^-$-collider under development by the CLIC accelerator collaboration,
hosted by CERN. The CLIC accelerator has been optimised for three energy stages
at centre-of-mass energies 380 GeV, 1.5 TeV and 3 TeV. CLIC uses a novel
two-beam acceleration technique, with normal-conducting accelerating structures
operating in the range of 70-100 MV/m.
  The report describes recent achievements in accelerator design, technology
development and prototyping, system tests and beam tests. Large-scale
CLIC-specific beam tests have taken place, for example, at the CLIC Test
Facility CTF3 at CERN, at the Accelerator Test Facility ATF2 at KEK, at the
FACET facility at SLAC and at the FERMI facility in Trieste. Together, they
demonstrate that all implications of the CLIC design parameters are well
understood and reproducible in beam tests and prove that the CLIC performance
goals are realistic. The implementation of CLIC near CERN has been
investigated. Focusing on a staged approach starting at 380 GeV, this includes
civil engineering aspects, electrical networks, cooling and ventilation and
installation scheduling, transport. All CLIC studies have put emphasis on
optimising cost and energy efficiency, and the resulting power and cost
estimates are reported. The report follows very closely the accelerator project
description in the CLIC Summary Report for the European Particle Physics
Strategy update 2018-19.
  Detailed studies of the physics potential and detector for CLIC, and R&D on
detector technologies, have been carried out by the CLIC detector and physics
(CLICdp) collaboration. CLIC provides excellent sensitivity to Beyond Standard
Model physics, through direct searches and via a broad set of precision
measurements of Standard Model processes, particularly in the Higgs and
top-quark sectors.
