This chapter considers the problem of experimental observation of the excitation of Langmuir solitons by electron beam. Solitons play a principal role in modern theoretical physics and even in theoretical bio- and neurophysics. Solitons arise not only as a result of modulational instability; they exist in various branches of plasma wave. High-amplitude plasma waves manifest, under certain conditions, the modulational instability which results in their self-compression. The chapter describes the cavitons that are three-dimensional wave packets which collapse with time; hence, they are not Langmuir solitons. Physically, solitons of some types are quite close to collisionless shock waves. At the present stage, the soliton is regarded as a fundamental object in non-linear wave theory. It is even said sometimes that the soliton in non-linear wave theory is an analogy to the classical oscillator in linear oscillation theory. The energy excess implied by conservation laws is liberated in the form of ion acoustic waves which, in their turn, produce soliton fragmentation.