Since retail forex trading became available and possible, “supply and demand” have crept into its vernacular from trading in general, having originally been highly relevant considerations to [I]stock[/I] trading. They’re not so much conceptually relevant to understanding forex trading, though: they’re terms which everyone uses with subtly different meanings and understandings and assumptions, and they therefore cause far more confusion and misunderstanding than they resolve.
Their appropriate equivalents relevant to forex trading are “buying pressure” and “selling pressure”.
The relative proportions and interplay of buying pressure and selling pressure are what produce support and resistance, which are themselves an underlying aspect of “price action”.
Price Action is a way of trading, usually done on naked charts, based off of candle and chart formations, support/resistance, trendlines, etc.
Supply and Demand are the two main forces driving the market (like any other market). You’ll never know the real supply and demand on the market if you don’t have access to an order book, and you will never have, unless you work at a market maker or at an other member of the “smart money”.
But there are ways to follow and these changes of supply and demand, they are the Volume Spread Analysis and the works of Richard Wyckoff. I’m doing both of these, they are kinda similar, pretty good strategies.
Support and resistance are just technical definitions. Both price action and VSA uses them for example, and a lot of other methods, it is not a strategy (actually it can be, why not?), but more like just a tool.
Looking at those links about these strategies, they are not using volume on their charts, so I have absolutely no idea how they are trading supply and demand changes then. Must be some kind of black magic.