The most fundamental soup stock in Japanese cooking and deeply flavorful
Dashi can be translated into English as “Japanese soup stock/broth”. The deliciousness of plants and fish are extracted by just soaking these in water or simmering these in boiling water. In Japanese cuisine, a variety of dashi are used, including those made from kombu seaweed and katsuobushi/bonito flakes, from just katsuobushi, from dried sardines, from kombu and from shiitake mushrooms, and from many more ingredients. By combining the delicious flavor from inosinic acid in katsuobushi with the glutamic acid in kombu, the resulting mixture has much deeper flavor than dashi made from either of these ingredients alone.
There is Ichiban dashi which is clear and uses boiled katsuobushi and kombu, and Niban dashi which uses the katsuobushi and kombu used in Ichiban dashi. The former is used as a clear soup or in dishes of boiled greens, and the latter pairs well with miso soup or vegetable dishes that are simmered in soy sauces.
Bonito dashi contains amino acids, and kombu dashi is packed with minerals. Also, using dashi in cooking will help to keep the dish tasty while keeping down the salt content.
There are research papers stating that dashi's flavor and aroma have a relaxing effect.