"It had been on the tip of his tongue to say "Except the proles" but he checked himself . . . "The proles are not people..." (pg. 53)
The proletariat is defined as the lowest social class, especially a class of works who sell their labor. In 1984, the Proles make up a huge percentage of the population (75%) and are generally left alone by the Party and the other Party members. Winston knows that the only way that the Party would ever be overthrown would be if the Proles rose up and took over. Orwell's characterization of the Prole reflects the idea if the people of the world remain content while politicians take over, the only way to reverse it is to rise up again. Orwell's serves as a warning against the government gaining too much power and the role of the Proles is to warn the world against being apathetic to the government gaining too much power.