WAVE Geomtery Linker is a means of associatively (or not if desired) linking (copying)geometry from one part into another. These can be bodies, faces, curves, sketches, routing objects etc which can then be used in the receiving part to design from or refer to. A simple example, if I create an assembly made up of 2 components, one being a container the other the lid or cover of the contatiner. Lets say I create the container first, I can then use WAVE Geometry Linker to associatively copy the top face of the container or the edges into the lid component. I then extrude this linked geometry (its shown in the part navigator as such) to create my lid. If the container changes size or shape then so will the lid as its linked.
Two key uses of WAVE are for manufacturing stage modeling and top-down design.
With manufacturing stage modeling you can create for example the casting form of the part and WAVE link that geometry into a new part to create the machined features and the end component. This has the advantage of having models and drawings for each stage of the manufacturing process and allows people to work on the same part simultaneously.
With top-down design you create a layout or concept model of your product with the key shapes and sizes. The geometry created is then linked into multiple component files where the detailed construction is created. These are then bottom-up assembled into the final product assembly. The advantage here is that you can easily make contolled design changes in the layout/concept model and then ripple these changes though into the detailed components.