It's no secret retail brokers are the counter party to all of your currency market transactions. When you execute your trade the opposite side of your trade is taken by another trader just like you. The resounding affect for the broker is they receive a commission for facilitating your trade. Now let's look at another means to facilitate your trade.
Rather than sending your trade to liquidity providers for processing there are market makers which take the opposite side of your transaction in order to assist facilitating the trade. A Market Maker may decided because the feel your going to lose anyways it benefits email list them to take your order and keep in house. In the first instance where one trader is available to take the opposite side of your trade is ideal until there is no volume then you get to understand an ECN and STP broker.
With an ECN and STP you are submitting market orders. Market Orders get filled when there is the volume to do so otherwise you get off quotes which tell a trader nobody is willing to risk taking your trade/order. During times of high volatility such as economic news, spreads can widen with an ECN, STP and any other type of broker unless you have a broker which charges a fixed spread.