In hydroponics, the plants are grown outside the natural soil, either on porous growing media (substrates) or in pure nutrient solution (water culture). The most commonly used growing media, which are characterized by a balanced availability of water and oxygen, are rockwool, perlite, pumice, and coir dust. Furthermore, water culture systems without any solid media, such as floating, NFT, and aeroponics are mainly used for leafy vegetables. This chapter describes the advantages and disadvantages of hydroponics, along with the equipment and substrates used. The chapter examines soilless/hydroponic growing systems for vegetables, including crop nutrition and nutrient solutions, product quality in hydroponics, and the specifics of soilless cultivation of greenhouse vegetable crops. The chapter offers guidance on irrigation and plant protection practices in soilless cultivation. Finally, the chapter looks ahead to future trends in this area.