But its the buyers and sellers who set the prices. The more urgent it is for someone to sell, the lower the price he will accept. So if I’m selling something for £2.80 and I see that you are selling the same thing for £2.60, you’re going to sell a lot more than I am: so if I really want to sell today I need to drop my price below yours, say to £2.50.
Vice versa for buyers.
We’ve all been to markets in the street. Its very similar in the financial markets except its electronic.