Inflation is a general rise in prices across the economy.
This is distinct from a rise in the price of a particular good or service. Individual prices rise and fall all the time in a market economy, reflecting consumer choices and preferences, and changing costs. Inflation occurs when most prices are rising by some degree across the whole economy. The inflation rate is a measure of the change in prices over a specified period, most commonly 12 months - the annual rate of inflation. We typically hear about the annual inflation rate for a particular month.