Core inflation

Inflation excluding food and fuel, which are the volatile components driven by weather and global commodity prices rather than by domestic demand.

The exclusion is not a trick to make the number look better. Monetary policy works on demand, and a monsoon failure is not a demand problem, so responding to a food-price spike with a rate increase would tighten conditions for no reason.

Persistent core inflation is the signal that price rises have become general, which is what central banks act on.

Headline moves the news. Core moves policy.