Recent ultra-short high-power lasers can provide ultra-high laser intensity over 1022 W/cm2
. Laser fields of such
extreme strengths instantaneously turn matter into plasma, which exhibits relativistic collective dynamics, thereby
leading to unprecedented physical systems with potential breakthrough applications. In this article, we introduce
the basic concepts and trace the progress in ultra-high intensity laser development and relativistic laser-plasma
interactions, including laser-driven charged particle acceleration.