The UK's inflation rate climbed to 3.5% in September, marking the highest level in nearly a year and exceeding the Bank of England's 2% target. This increase was slightly higher than economists had anticipated, primarily due to a surge in petrol and diesel prices. The Office for National Statistics (ONS) tracks inflation by monitoring a basket of everyday goods, including food and fuel, with updates reflecting changing consumer trends. The Consumer Prices Index (CPI) is the main measure used, and it is published monthly to inform the Bank of England's interest rate decisions.