The main distinction in types of monoplane is how the wings attach to the fuselage:
Although they are now the norm, the popularity of monoplanes has varied through the history of flight.
Louis Bleriot flew across the English Channel in 1909 in a mid-wing monoplane of his own design. The Fokker 'Eindecker' of 1915 was a successful fighter aircraft.
Monoplanes went out of fashion again, until after 1930. Most military aircraft of WW2 were monoplanes, as have been all turbo-jet powered aircraft since.