Gareth Alexander talks about knots in liquid crystals. In the past four years it has become possible to make knotted configurations experimentally in laser light, fluid flows and liquid crystals. Furthermore, recent advances in microfabrication offer the possibility of almost arbitrary experimental control in making such states. He will describe their recent work on how knotted textures in liquid crystals can be characterised using traditional knot theory and applied topology and how the material properties are influenced by the knot type.