Because this can be a subjective experience, it is often said that "beauty is in the eye of the beholder."
There is evidence that perceptions of beauty are evolutionarily determined, that things, aspects of people and landscapes considered beautiful are typically found in situations likely to give enhanced survival of the perceiving human's genes.
The classical Greek noun that best translates to the English "beauty" or "beautiful" was κάλλος, kallos, and the adjective was καλός, kalos.
However, kalos may and is also translated as ″good″ or ″of fine quality″ and thus has a broader meaning than only beautiful.