Which are properties of an electromagnetic wave?

-Electromagnetic waves carry transverse vibrations in electrical and magnetic fields, not vibrating particles.
-Electromagnetic waves do not need matter to travel through - they can travel through empty space (a vacuum).
-In a vacuum, all electromagnetic waves travel at approximately 3 x 108 m/s - the fastest speed possible.
-When electromagnetic waves travel through matter (for example, light through air or glass), they travel a bit slower than this but rarely less than half as fast as in a vacuum. The value for light travelling through an optical fibre, for example, is taken as 2 x 108 m/s.