They are simply notes to you. Following comments are nodes. Nodes describe shapes, light, sounds, etc. Within the nodes are fields and values. Fields describe node attributes.
Fields are optional and given in any order and values are attribute values.
In order to bring life to a VRML world shapes are used. Shapes are the building blocks of a VRML world. To build these shapes, a shape node is use. A shape node builds shape, appearance and geometry. Appearance defines color and texture.