X_train, X_test, y_train, y_test = train_test_split(X, y, test_size = 0.25, random_state = 0) …whats the significance of random_state=0?

Question

What\'s the significance of random_state=0 in this particular line "X_train, X_test, y_train, y_test = train_test_split(X, y, test_size = 0.25, random