Quantum field theory is a way of looking at how the world works that combines ideas from quantum mechanics and Einstein's theory of relativity. In quantum field theory, particles (like atoms and electrons) are seen as vibrations or energy fields that fill all of space. These fields interact with each other, bouncing around and changing shape like a wave in an ocean. This means that particles are no longer seen as tiny objects that move around in space, but more like ripples in a vast ocean of energy.