Edlp (low price every day): Or "everyday parity", which was first put forward by Wal-Mart in the United States, has been widely used by various businesses. It refers to the price strategy adopted by discount retailers (such as general supermarkets), that is, to keep the price and gross profit low every day to attract a large number of passengers to spend. It is different from the "HI-LO" promotion strategy of non-food companies.