Forex trading is similar to trading shares or futures except that when trading foreign exchange you are buying or selling one currency against another and you do not take delivery of the underlying currency. One of the key advantages Forex has over other financial instruments is that relatively small lot sizes can be traded - lot sizes can be as small as 1000 units (one micro lot). Typically, foreign exchange also involves leverage which in some cases can be as high as 1:500, which is very different to trading shares where no leverage is involved.