The Consumer Price Index (CPI) measures the change in the price of goods and services from the perspective of the consumer. It is a key way to measure changes in purchasing trends and inflation.
A higher than expected reading should be taken as positive/bullish for the GBP, while a lower than expected reading should be taken as negative/bearish for the GBP.
The FOMC usually changes the statement slightly at each release. It's these changes that traders focus on. It's the primary tool the FOMC uses to communicate with investors about monetary policy. It contains the outcome of their vote on interest rates and other policy measures, along with commentary about the economic conditions that influenced their votes. Most importantly, it discusses the economic outlook and offers clues on the outcome of future votes.