The interaction of relativistically intense laser radiation with plasma is rich in nonlinear processes like laser pulse self-modulation and self-focusing, wake-field excitation, wave-breaking and the creation of relativistic solitary structures. The creation and evolution of solitary structures during relativistic laser-plasma-interaction is discussed in this book. A relativistic Maxwell-fluid model is formulated to investigate these solitary structures. We discuss the creation of pre-solitons and their transition to post-solitons. The longitudinal and transversal stability of stationary...