Textbook in PDF format This book describes the possible distribution of life in the Milky Way. Our description is mathematical in order to be extrapolated from what we know that happened on Earth to what might have happened on the huge number of extrasolar planets existing in the Milky Way Galaxy. We use the statistical Drake equation, which identifies parameters for calculating the total number of life forms at all levels. While the original Drake equation (1961) contained seven factors only, we extend the number of factors to 50, thus incorporating much of the scientific knowledge about the Evolution of Life available in 2024