中文：

CPI是消费者物价指数的缩写，是反映一定时期内城乡居民所购买的生活消费品和服务项目价格变动趋势和程度的相对数。它是宏观经济分析和决策的重要指标之一，也是进行价格指数连锁分析和计算通货膨胀率的重要依据。

CPI的编制目的是观察消费物价指数的变化趋势，以反映消费者的购买力变动情况。其编制方法是按照全国城乡居民在一定时期内对各类商品和服务的消费支出进行抽样调查，并按照消费品和服务的价格水平进行加权平均，从而得到一个能够反映全国居民在一定时期内对各类商品和服务的消费支出的综合价格指数。

CPI的优点是能够反映消费者的购买力变动情况，可以帮助政府了解民生问题，同时也是进行价格指数连锁分析和计算通货膨胀率的重要依据。但CPI也存在缺点，如编制方法不够精确、受季节因素影响等，需要进一步完善。

总的来说，CPI是宏观经济分析和决策的重要指标之一，对于了解国内经济发展情况和政策制定具有重要意义。

英文：

CPI is the abbreviation for Consumer Price Index, which is a relative number reflecting the price trend and degree of changes in the prices of consumer goods and service items purchased by urban and rural residents in a certain period of time. It is one of the important indicators for macroeconomic analysis and decision-making, as well as an important basis for chain analysis of price indexes and calculation of inflation rates.

The purpose of CPI is to observe the trend of changes in consumer prices to reflect the changes in consumers' purchasing power. Its method of preparation is to sample the consumption expenditure of urban and rural residents nationwide in a certain period of time, and weighted average the prices of consumer goods and service to obtain a comprehensive price index reflecting the consumption expenditure of various goods and services of residents nationwide in a certain period of time.

The advantages of CPI are that it can reflect the changes in consumers' purchasing power, help the government understand the problems of people's livelihood, and also an important basis for chain analysis of price indexes and calculation of inflation rates. However, CPI also has some shortcomings, such as the method of preparation is not accurate enough, affected by seasonal factors, etc., which need to be further improved.

Overall, CPI is one of the important indicators for macroeconomic analysis and decision-making, which is of great significance for understanding the development of the domestic economy and policy formulation.