Low inflation has been a puzzle for economists. A model combining money and growth factors predicts central banks will struggle to reach 2% inflation targets, which has been true. Inflation is mainly influenced by changes in currency value and long-term monetary trends. Factors like population growth and interest rates also play a role. In advanced economies, real growth factors have been declining, leading to lower inflation rates. Central banks are more likely to face zero inflation or deflation than reach their 2% targets due to these trends.