1. Core: This is the innermost layer, where nuclear fusion takes place. It's incredibly hot and dense, and responsible for generating the Sun's energy.

2. Radiative Zone: Surrounding the core, this layer is where energy from the core is transported outwards through radiation. It's still very hot, but less dense than the core.

3. Convective Zone: The outermost layer, where energy is transported by convection. This means hot gas rises and cooler gas sinks, creating a continuous cycle.

While these are the three main layers, it's important to note that there are also other regions of the Sun, like the photosphere (the visible surface), chromosphere (a thin layer above the photosphere), and corona (the outermost layer).