Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk. (Wikopedia)
Advantages of hydroponic gardening are:
No soil is needed
The water stays in the system and can be reused - thus, lower water costs
It is possible to control the nutrition levels in their entirety - thus, lower nutrition costs
No nutrition pollution is released into the environment because of the controlled system
Stable and high yields
Pests and diseases are easier to get rid of than in soil because of the container's mobility
Today, hydroponics is an established branch of agronomy. Rapid progress and results obtained in various countries have proved it to be thoroughly practical and to have very definite advantages over conventional methods of horticulture.
HYDROPONIC read all about it here!