If you're referring to the buyers and sellers in the market depth then bear in mind that most genuine buyers and sellers don't declare their hand by placing their orders in the depth but rather buy/sell when they see an order worth taking out. Or they stagger the buying/selling over the day by placing lots of smaller orders. In addition some of the orders in the depth may not be genuine and are used to prop up the price or deter buyers. They can disappear without warning.
All is not what it seems though you learn to spot them after a while.
