A square matrix is row stochastic if all the entries are non-negative and the entries in each row add up to 1. It is column stochastic if all the entries are non-negative and the entries in each column add up to 1. A square matrix is stochastic if it is either row stochastic or column stochastic, such as a transition matrix. It is doubly stochastic if it is both row stochastic and column stochastic.