Inflation is a general trend of increasing prices.
You might be surprised to hear there is also such a thing as deflation, or generally decreasing prices, because we haven't seen that phenomenon in the United States in more than 50 years. As measured by the Consumer Price Index, prices are now 15 times what they were before World War I, and four times what they were in 1970. When demand for goods or services exceeds the supply, the providers of these goods and services tend to raise their prices. When a company passes increased production costs along to its customers, this is cost-push inflation. Higher prices trigger all sorts of other inflationary behavior, such as workers everywhere demanding higher salaries, which causes producers to raise their prices again, and so on.