Ultraintense laser radiation transforms matter into plasma rich with free energetic electrons. Controlling the distributions and flows of these electrons enables to generate and shape the record electric and magnetic fields suitable for many applications. Our research scope extends from the fundamental studies of highly nonlinear laser-plasma interactions, to their applications in the compact accelerators of electrons, ions, and sources of bright femtosecond X-rays. We also look for the potential applications of these laser-plasma particles and X-rays sources in medicine, radiotherapy, radiobiology, and for non destructive material inspection.