Logic behind the stationary distribution

Suppose you are given the following transition matrix:

P = np.array([[0.15, 0.75, 0.10],
              [0.95, 0.0, 0.05],
              [0.45, 0.20, 0.35]])

Explain what a stationary distribution is and how to calculate it. Then, use the given transition matrix above and find the stationary distribution.