Theory of everything
Unified field theory is a hope for a theory of fields in physics that will explain all natural phenomena. Theories in physics can be very different and even disagree with each other. This is true for example for quantum mechanics (the science of very small things) and general relativity (the science of space and time). The goal of unified field theory is to take all the different parts of physics and combine them into one theory that explains everything. The Standard Model comes close to a unified field theory, combining everything except general relativity.