Dashi is a broth of a few basic fundamentals are in Japanese cuisine.

The most common form of dashi is a simple broth prepared by boiling seaweed, called konbu, and dried bonito flakes, called katsuobushi, keeping only the resulting liquid. The fresh dashi is rare these days, even in Japan. Most people use substitutes instantaneous liquid or granules.

Dashi is the base of miso soup, broth for noodles and other Japanese cooking liquids of this kitchen.

Other kinds of dashi are prepared by soaking seaweed, shiitake or niboshi in water for several hours or by heating them nearly to the degree of boiling, and finally collecting the liquid portion:

Dashi konbu (seaweed broth) was prepared by soaking algae in water.
The shiitake dashi is prepared by soaking in water shiitake.
The niboshi dashi is prepared by soaking small dried sardines, whose head and entrails were removed, in water.