The review describes the present status of the physics of optical pulse self-action phenomenon. A brief analysis of linear propagation of ultrashort laser pulses in dispersive media and optical elements is given. Results on self-phase-modulation and on profile shock waves in media with various group velocity dispersion are presented. The problems of optical pulse compression and the possibilities to control their shape are discussed in detail. Particular attention is paid to the physical aspects of formation and interaction of optical solitons. Stochastic problems of temporal self-action are also discussed. In conclusion the promising directions in nonlinear optics of femtosecond laser pulses are discussed.