Who are the proles and what are their importance to the story?

The proles are the working people -- the ones who provide
all the more physical and manual labor that needs to be done in the society.  For
example, they serve the food at the cafeteria at Winston's workplace.  They make up
about 85% of the society.

To me, the main importance of the
proles to the story is that Winston thinks that they are the society's hope for the
future.  He seems to think that they are more closely connected to what people used to
be like -- they have more "human" lives than they people in the Party who are constantly
monitored.  He thinks that they are much more likely also to be able to get together to
start a rebellion because they are not monitored.