Mako Reactor No. 1 is the first of eight such reactors. These reactors are used to harness the life energy of the planet, also known as Mako. While this is indeed dangerous and it harms the planet, this energy is used towards making life better for the people of Midgar. Mako energy is also used in the making of Materia, magical stones that the people of the world use for various purposes. These purposes include: using magic, combining certain materia for added effects, the ability to perform certain actions, used for summoning powerful creatures, and for applying certain effects to your weapon(s). Finally, each reactor is actually built like a factory. There are many floors to each Mako Reactor, there are many people that both work in and guard the reactors, and there are various devices inside used to harness the energy of the planet.