What an order book is
Behind every stock price sits an order book: a live, constantly updating list of all the buy and sell orders waiting to be filled. It shows not just the current price, but how many shares people want to trade at each price just above and below it. The exchange matches buyers and sellers from this book, trade by trade, all day long.
Bids, asks, and the spread
The book has two sides. Bids are buy orders — the prices buyers are willing to pay, sitting just below the current price. Asks (or offers) are sell orders — the prices sellers want, sitting just above. The gap between the highest bid and the lowest ask is the spread. A tight spread means buyers and sellers nearly agree; a wide spread means they don't, which is common in thinly traded stocks.
What depth and walls mean
Depth is how many orders are stacked at each price level. When a lot of orders pile up at one price, traders call it a wall. A big green bid wall below the price means strong buying interest waiting there; a big red ask wall above means heavy selling interest. Walls show you where the real demand and supply sit, beyond just the latest traded price.
Why walls act like support and resistance
A large bid wall can act as support — price often struggles to fall through it because so many buy orders must be filled first. A large ask wall can act as resistance, capping price rises. But walls can be pulled or moved by big traders, so they are a clue, not a guarantee. Reading the book tells you where pressure is building right now.
Push buy and sell pressure above until you can see the walls shift — then take the quick check below.