Modern simply means "up-to-date" but the term modernism connotes a rejection of conventions and a commitment to radical innovation. Like scientists and inventors, modern artists engaged in a process of experimentation and discovery. They were seeking to explore new possibilities of creativity and expression in a fast changing world.
After 1900 the pace of artistic innovation increased, producing a lot of successfull new movements, avant-gardes, and also called "isms", including
Fauvism ("The Wild Beasts" french movement including Henri Matisse)
Cubism (Pablo Picasso and Georges Braque as pioneers)
Futurism (Italian movement, passion for an industrial world)
Dadaism (Movement started in Zurich, included members such as Hugo Ball and Marcel
Duchamp and Jean Arp.)
Surrealism (Movement started in Paris and included members such as Salvador Dali and
Max Ernst.)