Ebb and Flow Systems require a medium, such as perlite, which serves no purpose other than to provide stability for the plant’s roots. The plant derives no nutrients from the medium itself. Ebb and flow systems include a tray in which the plant is placed in a medium; below the tray in a separate container is a reservoir containing water and mineral solutions. The water from the reservoir is periodically pumped up into the tray.  [Source: Howstuffworks]

Nutrient Film Technique (NFT) is a water-based system that requires no soil or mediums. They’re built using wooden channels, which support polyethylene film liners. Plants are placed on the channels, and the nutrient enriched water is pumped to the high end of each channel. Only plants with large established root systems will work with this technique. [Source: Howstuffworks]

Drip Systems are set up almost identically to an ebb and flow system, although instead of water being pumped through one large tube, it’s pumped through many small tubes and drains onto the top of the plants. This system is ideal for plants that don’t yet have a developed root system, and like an ebb and flow system, works best with smaller plants. [Source: Howstuffworks]

Aeroponics is another water based system, which, like NFT, requires no medium. Plants are suspended on a tray, with their roots freely dangling below. The entire tray is placed into a box that has a small amount of water and nutrient solution in the bottom. A pump system is used to draw the water up, where it’s sprayed in a fine mist onto the entire plant and root in a continuous manner. This system is the most difficult to set up and manage. [Source: Howstuffworks]

Wick Systems are similar to ebb and flow systems in that they’re medium-based. Plants are placed into a tray filled with a medium such as perlite or rockwool. At the base of each root, a nylon rope is placed, which is allowed to dangle freely, extending beyond the bottom of the tray. The entire tray is then placed on top of a reservoir. The nylon ropes absorb the water and nutrients, wicking them up to the plant’s roots. This system is desirable because it requires no pumps or other equipment to be purchased. [Source: Howstuffworks]