Distinguish the time period of both modernism and postmodernism.

The modern period, roughly spanning from 1900 to 1930, marked a significant shift in artistic and literary movements, while the postmodern period emerged around 1945, following World War II, and gained prominence from the 1960s onward. It's important to note that these movements cannot be strictly confined to specific dates, as artistic and literary developments evolve gradually and do not adhere to a precise timeline.