【中文版】

CPI是消费者物价指数，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。

CPI是宏观经济运行监测指标，它不仅反映居民消费物价变动情况，还具有反映通货膨胀或紧缩程度的功能。在居民消费物价指数中，包括食品、衣着、家庭设备用品及服务、医疗保健、交通和通信、娱乐教育文化服务、居住、杂项商品和服务等类，共200多项。

CPI通常是以一个基期为参照标准，以某一个特定时期为基期，将当期与基期相比较，计算出相对变化率，以此作为反映通货膨胀或紧缩程度的指标。因此，CPI也是一个相对数，可以用于不同时期之间的比较，以反映价格变动的趋势和程度。

在我国，CPI一般是指城镇居民消费物价指数，这是因为城镇居民消费占据了全国总消费的绝大部分。此外，由于城乡居民消费结构存在差异，因此将城镇居民消费物价指数与农村居民消费物价指数分别编制，以便更准确地反映不同群体的消费价格变动情况。

总之，CPI是反映我国居民消费价格变动情况的重要指标，对于宏观经济运行监测和政策制定具有重要意义。

【英文版】

CPI, which stands for Consumer Price Index, is a relative number that reflects the price trend and magnitude of consumer goods and service items purchased by urban and rural residents within a certain period.

As an important monitoring indicator of macroeconomic operation, CPI not only reflects the change of consumer prices, but also reflects the inflation or deflation degree. In the consumer price index, there are more than 200 items, including food, clothing, household equipment and services, medical care, transportation and communication, entertainment, education and cultural services, housing, miscellaneous goods and services, etc.

Usually taking a base period as the reference standard, CPI compares the current period with the base period to calculate the relative rate of change, which is used as an indicator to reflect inflation or deflation. Therefore, CPI is a relative number that can be used to compare different periods to reflect the trend and degree of price changes.

In China, CPI usually refers to the Consumer Price Index of urban residents, because urban residents' consumption accounts for the majority of the country's total consumption. In addition, due to differences in consumption structure between urban and rural residents, the Consumer Price Index of urban residents and that of rural residents are separately compiled to more accurately reflect the price changes of different groups.

In short, CPI is an important indicator reflecting the change of consumer prices in China, which is of great significance to macroeconomic operation monitoring and policy making.