1.) If I buy a currency, I buy it from a trader (participant of a trading platform) like myself, right? As if I download a song from a peer-to-peer platform like emule or so, right?)
The broker/market-maker is “only” a middle-man/intermediator, right?
And he takes hes fee, which is his spread (some pips), right?
2.) If I sell a currency pair, means, another participant (“peer”) on the trading platform, buys a certain currency from me, right?
You buy or sell to your dealer. On the retail level the dealer (aka broker) always takes the other side of the trade, unless you are dealing through an ECN or some other pass through broker (straight through processing). In those cases either a network of dealers or a single dealer will take the other side of your trade. But for most retail trades, they never end up with the large bank dealers, they just end up on the books of their broker or their broker’s liquidity provider. So in the end you will end up with a dealer on the other end of your trade unless you trade through an ECN and another customer happens to be offering liquidity at the same time you are there demanding liquidity (or vice versa). So to recap::
No you buy/sell to/from your dealer.
Unless you are dealing through an ECN the answer is your trade is taken by a dealer that may then lay it off on some other dealer or keep it for its book of business.
If you want to learn more about this topic, search for market microstructure. Larry Harris’ book is probably the authoritative book on the subject right now “Trading and Exchanges”
Forex is actually a negative sum game because of the spread but that’s a whole discussion unto itself.
There are really two classes of traders. Liquidity providers are banks and others who take the other side of orders. In the retail forex market, it is the fx dealers who most often take the other side of trades. If you dig into who the liquidity providers are for a given broker, you will find that even with the ECN brokers, they state that they are the liquiidty providers 9.9 times out of 10 (when you read the small print). Because retail forex dealers are the market, retail forex traders are unable to capture the spread or act as liquidity providers. The exception is with real markets like the forex futures, or with some forex ecns that allow trading between all market participants. Liquidity providers don’t trade between themselves on these platforms. That is usually part of their agreement to provide liquidity or a constant bid/ask quote.
Liquidity takers are all those traders who demand liquidity by buying at the current ask and selling at the current bid, or who come into the market as most retail traders do and place trades to enter when certain fundamental, technical or other trigger occurs. Liquidity takers pay a premium for demanding an immediate price fill. One part of this premium is the ask-bid spread. The other part of this premium is often referred to as slippage by traders, a cost of demanding liquidity during fast moving or highly volatile market movements.
The reason there is always enough liquidity is that liquidity providers must make a market by quoting a continuous bid/ask spread. These prices are “the market” for a given forex retail broker. Unfortunately many of the “tutorials and diverse introductions into Forex” are ignorant of the true market mechanics. As I previously stated, you don’t need to take my word for it. Please do some research into “market microstructure” and you will be able to recognize truth from myth in the articles that you read.
The questions you are asking are perhaps more advanced than this site. Attempting to understand the true nature of the markets you trade should be the starting point for all traders. There are some really good discussions on this topic on that other fx factory. Good luck!
A correction needs to be made here. There isn’t actually anying buying or selling in retail forex trading. No currency ever changes hands. When you go long or short you are transacting in contracts to do future exchanges (yes, buy/sell is used to mean long/short). As noted previously, these contracts are either made with your broker acting as dealer, or with some other market maker (liquidity provider) elsewhere in the market. They are, in turn, looking to match their position with you with one with someone else to lock in a spread profit.