What is after hour trading?
The trading which is conducted after the market has been closed is given the term of after hour trading. However, this is a time when the trading is not that much with the prices also being extremely fickle. The stock market trading is also conducted after the regular working hours and here one of the aspects that takes place is that when the user gives an order for acquiring a stock after the market is closed then that stock gets acquired automatically if the market opens at an increased price.
There are pre and post market hours. Spreads are wider and there is little good reason to trade in them. The prices also move more erratically as in any really thin market. A stock I was watching this morning traded at 42.00 and then at 43.14 next trade. Your broker is also likely to charge you more. Forex is not an after hour market. It is completely separate and trades currencies only.