This is the beginning of a new series on Marxist-Leninist theory. Fight Back! News is publishing this series of short articles in the interest of furthering the critical task of fusing Marxism with the workers’ movement. Marx stressed that the purpose of theory is to understand the world so as to change the world, and this series hopes to help give activists in the people’s struggles a better grasp of these theoretical tools. But let’s begin with an overview: when we say we are Marxist-Leninists, what does that mean? What is Marxism-Leninism, and why is it important?