A review is presented of most promising string cosmology models based on concepts from string and heterotic M theories. Possible scenarios are discussed for the beginning and evolution of the universe. In all models as in standard cosmology the problem of particle-antiparticle asymmetry arises, the issue is that all models predict equal number of matter and antimatter to exist in the universe. This contradicts the observations that the number of antiparticles is much less than the number of particles. Interpretation of this phenomena based on the CP violation are widely accepted in the literature. However, alternative interpretation is given in which particles and antiparticles were distributed in a brane and antibrane, respectively, immediately after the collision. In the present work implications of this scenario are discussed in detail. Particularly, the possible formation of a universe and an antiuniverse is discussed with emphasize on the existence of different types of gravity.