To give a precise definition of Biostimulants, the Ebic (European biostimulants industry council) has stated:
"Biostimulants contain substances or microorganisms whose function, when applied to the plant or rhizosphere, is to stimulate natural processes to increase or improve nutrient absorption, tolerance to abiotic stress, and crop quality."
Biostimulants are substances typically extracted from plants or microorganisms that are used in agriculture and act on natural physiological processes, helping the plant to "perform better".
Biostimulants do not actively counteract attacks from pathogens or phytophagous insects. They make the plant stronger against abiotic stresses such as heat, cold, or water deficiency, increase nutrient absorption efficiency, and improve crop quality.