The following diagram shows my preferred method for wiring a domestic 2-way lighting circuit. In this context, 2-way implies that two switches attach to the same light.
In the above diagram, the Supply and Light cables are standard 3-core (Live, Neutral and Earth). The Switch cables are special 4-core used specifically for this type of circuit. A six-terminal junction box is required and only one supply can be wired to it. If the junction box has to be part of a ring then a standard four-terminal junction box will also be required to link Supply-In, Supply-Out and Supply to the six-terminal box. When wiring the six-terminal box a good simple check is to ensure that all terminals (except the Earth) have two wires.