中文：

KDJ指标是一种常用的技术分析指标，它是由三条线组成，分别是K线、D线和J线。这些线是通过比较最高价、最低价和收盘价之间的关系来反映股票价格的波动情况。

K线是一条快速线，它表示的是最近三个周期内的最高价和最低价之间的差距。D线是一条慢速线，它表示的是最近十个周期内的最高价和最低价之间的差距。J线则是对K线和D线的延伸，当K线和D线形成金叉时，J线会先于K线和D线向上延伸，当K线和D线形成死叉时，J线会先于K线和D线向下延伸。

KDJ指标的主要作用是判断股票价格的趋势和买卖信号。一般来说，当K线和D线向上交叉时，说明股票价格处于上涨趋势，可以考虑买入；当K线和D线向下交叉时，说明股票价格处于下跌趋势，可以考虑卖出。同时，J线的向上或向下延伸也可以提供更加及时的买卖信号。

总的来说，KDJ指标是一种简单而实用的技术分析工具，它可以帮助投资者更好地把握股票价格的波动和趋势。

英文：

KDJ is a commonly used technical analysis indicator composed of three lines: the K line, D line, and J line. These lines reflect the volatility of stock prices by comparing the relationships between the high price, low price, and closing price.

The K line is a fast line that represents the difference between the highest and lowest prices of the last three periods. The D line is a slow line that represents the difference between the highest and lowest prices of the last ten periods. The J line extends K line and D line. When K line and D line form a golden cross, J line will extend upward before K line and D line. When K line and D line form a dead cross, J line will extend downward before K line and D line.

The main function of KDJ is to judge the trend of stock prices and provide buy/sell signals. Generally speaking, when K line and D line cross upward, it indicates that the stock price is in an upward trend and can be considered to buy; when K line and D line cross downward, it indicates that the stock price is in a downward trend and can be considered to sell. At the same time, the upward or downward extension of J line can also provide more timely buy/sell signals.

Overall, KDJ is a simple and practical technical analysis tool that can help investors better grasp the fluctuations and trends of stock prices.