Now go outside and look at the sky.
It would be an understatement to say that propaganda posters had an important role in how the Chinese Communist Party communicated with the public.
Especially in the early years of the People's Republic, when radios were still sparse and travel was hard, a few strategically placed posters in each town and village were maybe the only reinforcement of what the party leadership thought was the right way to do things.
Many of these posters are amazingly colorful and and - in retrospect - charming in their naivety, while some of course have lost nothing of the poignancy. Stefan Landsberger has a large collection of these posters on his site and he is probably one of the leading western experts to share his knowledge about this specific art form on the net.