Aleksandr Lyapunov, the man who created the modern theory of stability

The outstanding Russian mathematician Aleksandr M. Lyapunov passed away one hundred years ago, on November 6, 1918. Honouring his memory, we recall the main events of his life when he was a student, then from the years in Saint Petersburg until 1885, from the Kharkov period, finally from his second period in Saint Petersburg from 1902. We recount the main fields of his scientific activity (stability theory, potential theory, probability theory, shape of planets) concerning stability theory and chaos in details