What is forex, and how does it work?

Tweet

So, I heard some onliners have discussion about forex.com, and what is this all about? Can anyone tell me? I went into that website and took a peek myself. It is an online trading site, which I am not familiar with international trading, and I always thought it would be risky. The major product they trade about will be currency. I just wonder how do this website work, and did anyone earn money from it? Do share with me, please I am curious about it.