If you've ever tried to use any type of adult toy without lube, you're fully aware of how important this slippery liquid is. It provides a barrier between your skin and the surface and allows you to glide well. During sexual intercourse women produce wetness inside the vagina but sometimes this is not enough, furthermore many women have vaginal dryness and even with clitoral stimulation the vagina does not get wet enough for comfortable penetration.
Enter lubrication into the picture and you've instantly got yourself a slippery slide to pure enjoyment. Water based and silicone each have their own properties and we prefer water based for intercourse and silicone for masturbation.