This book presents advances in x-ray spectroscopy of plasmas interacting with a laser radiation and laser-induced plasmas. This research is practically important for the quest for the controlled nuclear fusion, for studying matter under extreme conditions, for providing atomic reference data, for laboratory modelling of physical processes in astrophysical objects, and for a better understanding of intense laser-plasma interactions. This book significantly expands the scope of practical applications of x-ray spectroscopy of laser plasmas compared to traditional x-ray diagnostics of laser plasmas. The recent advances presented in this book enable studying the development of Langmuir waves, ion acoustic waves, transverse electromagnetic waves, parametric decay instabilities, as well as the rates of charge exchange between multicharged ions. Key Features Presents novel methods of the x-Ray spectroscopy for both non-relativistic and relativistic laser-plasma interactions Includes novel methods of the x-Ray spectroscopy for measuring ultra-intense magnetic fields in laser plasmas Examines advanced designs of plasma-tunable x-ray lasers Demonstrates various analytical formalisms underlying the advances described in the book