Pheno hunting is the process of searching through many plants of a particular variety to find one (a phenotype) with dominant traits desired by the grower. These traits include, but are not limited to color, flavor, smell, and cannabinoid content as well as growth characteristics such as resistance to pests, overall height, total flowering time, and average yields.
How to stabilize a strain
By seeking out a phenotype with specific traits and crossing it with a phenotype with other traits, growers are able to (over several generations) stabilize the strain to exhibit the desired traits from each parent seed. Another application of pheno hunting to stabilize a strain would be a breeder crossing two strains to make a new one and choosing the best pheno of the new strain to cross with itself. Some new strains are more stable than others. Stable strains tend to produce fewer phenotypes, leading to more predictable results when cultivating the strain.