In a nutshell
Unlike traditional bookmakers, who offer a fixed price, the Betfair Exchange allows customers to ask for a better price if they don't like what is being offered.
How does it work?
An Exchange market will show the prices on offer at any given time in the blue (back) and pink (lay) boxes.
To request a better price - sometimes known as 'submitting an order' - you simply click on the price, but manually alter the odds, using the arrow keys.
Your bet will be placed in the market and, if accepted by another customer, will be matched at those odds.
When you ask for better prices there is no guarantee that another Betfair customer will be willing to accept the price you are offering or asking for, but with odds often changing rapidly, it's a good way of getting more bang for your buck.