Modernism and Postmodernism

Ok so after some correlation between my old napkin and moodle, I've managed to ascertain that it was in fact "Post Modernism" that I'd scribbled down all those months ago. (The 'post' was hidden in a crease) So I'll start with that.
According to "Answerer 1"(2010) on Yahoo answers (he/she) claims Modernism; 'is the study of very modern fence making.' "Anonymous" (2010) goes on to state Post-modernism; 'is supposed to mean after the Civil War, but its meaning keeps changing.'
I considered these sound starting points to base this entry on, however a few google hits later, these statements were proved to be somewhat inaccurate...
Apparently Modernism encompasses a rough period from the end of impressionism around the 1800's to the start of Post-Moderism around 1970. It's general consensus was that there was a need for expressionism within art, that the viewer was as important as the creator in defining the work. Leaving things open to personal interpretation was key. A prime example of this is the infamous "Fountain" by Marcel Duchamp.

The upside-down urinal that he signed caused quite the stir among the gaggles of pretentious gallery go-ers at the time, when it was rejected from the apparently uncensored 1917 show by the Society of Independent Artists. Quite the fur-or I imagine...
The same movement gave way to the likes of Barnett Newman who liked to paint a canvass one vibrant colour, with a few of thin vertical lines somewhere on the canvas in one or two other colours.

  Well it's meaning lost on me... Oh that's right, I have to put meaning into it. Well I think it means the artist didn't have much time to paint. Frankly, I think its like one of those characterless printed canvases you see for sale in ikea or on the wall of high street salons. An inoffensive block of colour to brighten up the workplace. And yes he may well have been the first to do something like this, but does that make it genius? I'm not sure...

I could mention a hundred artists from this period of Modernism and similarities in terms of content would be scarce but if the philosophies and goals of the artists are taken into consideration, theres a pattern of a combined sense of drive towards expressionism over realism...

Hang on a minute, further extensive research via the web (aka wiki) now cites Newman and Duchamp in the Post Modernism section too... I'm extensively confused and from bouncing around the web it seems no-one has a clear answer as to who goes where, leaving me rather frustrated. Between Moderism, Post-Modernism, and all those bloody sub-genres it's anyones guess. All I know for certain is Metal Gear Solid 2 was referred to as the first Post-Modern video game... And I liked MGS-2.

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