The stock market is made up of exchanges, like the New York Stock Exchange and the Nasdaq. Stocks are listed on a specific exchange, which brings buyers and sellers together and acts as a market for the shares of those stocks. The exchange tracks the supply and demand — and directly related, the price — of each stock. (Need to back up a bit? Read our explainer about stocks.)
Sell walls: the action of artificially keeping the price of a cryptocurrency asset low by placing a large sell order. Large financial operators or investors (nicknamed « whales ») may want to artificially keep the price of a cryptocurrency low so that they can keep accumulating quietly, without causing a sharp rise in price. These are called « walls » because on exchanges, the graphics showing offer and demand will show a very high « wall » on the offer size. The mechanism is that the investor will put a very large sell order (usually 100 to 1000 times more cryptocurrency units than regular orders). Because of how exchanges operate, the sell will only take place if there is sufficient demand to fulfil the entire order, so smaller operators who have a real need/urge to sell would have to sell below that wall (i.e. cheaper) to make sure they can get paid. This will cause a condition where the price will stagnate, allowing those whales to put as much smaller buy orders as they need. Sell walls may be removed once the buying whales have reached their objectives.
Dollar-cost average: This sounds complicated, but it’s not. Dollar-cost averaging means investing a set amount of money at regular intervals, such as once per week or month. That set amount buys more shares when the stock price goes down and fewer shares when it rises, but overall, it evens out the average price you pay. Some online brokerage firms let investors set up an automated investing schedule.