From The Matrix wiki
Matrix
The Matrix is a sophisticated neuro-interactive simulation designed by sentient machines to pacify and harvest energy from the human population.
The Matrix functions as a digital construct that replicates the world of the late twentieth century, keeping the minds of enslaved humans occupied while their physical bodies are cultivated in pods. By maintaining this illusion, the machines ensure the cooperation of their captives, who provide the bio-electric power necessary for the machine city to survive.
Structure and Control
The simulation is overseen by programs such as the Architect, who designed the framework, and the Oracle, who provides guidance to those who seek truth. Security is maintained by the Agents, sentient software programs capable of manifesting within the construct to eliminate threats or anomalies that jeopardise the stability of the system.
Those who are unplugged from the simulation often join the resistance based in the underground city of Zion. Using hardline connections, these individuals can enter and exit the Matrix, where they possess the ability to manipulate the laws of physics, allowing for the advanced martial arts and combat skills required to oppose the machine threat.