The Harmonised Index of Consumer Prices (HICP) measures the average change in the prices households pay for a representative basket of goods and services. It is "harmonised" so every EU country is measured the same way and the figures are comparable.
Annual, monthly, headline
The annual rate compares prices with twelve months earlier — the standard "inflation is X%" figure.
The monthly series gives a more timely read between annual updates.
The eurozone headline rate is the single figure the ECB targets.
Why it matters
The ECB aims for 2% over the medium term. Inflation above that erodes the purchasing power of wages and savings; the effect compounds, so several years of moderate inflation add up to a large fall in what a euro buys. See the accumulated-inflation view on the euro page.
Source: Eurostat and ECB (HICP).