Hydroponics is the method of cultivation which requires no soil- plants are grown in an inert medium, such as rockwool or clay pebbles.
The main advantages of growing this way are that there is none of the mess of soil, growth is faster, and less root space is needed for the uptake of nutrients. This is because the roots are constantly bathed in nutrient solution by way of either a drip feed or flood and drain system, allowing faster intake with fewer roots, as they do not need to search for sustenance.This also means more growth gets put into the top of the plant esp. the bud!