An efficient market is one in which the prices of the assets traded in it reflect at all times the information available on the market.
Financial asset prices react strongly to market information. When the information is released, the different market agents analyze it and use it to make decisions. So this information is incorporated into the price as it arrives.
Therefore, the more information on the market, the greater the efficiency of prices and the greater reflection of the fundamental value of assets. In this way, an efficient market can be considered as a market in which assets are quoted at their fair price and this price also truly reflects their real value at all times.