What does a 'fall in inflation' mean?

Inflation as measured by the Consumer Prices Index fell to -0.1% in September, official figures have shown - but what does that mean?

The Office for National Statistics (ONS) said that a smaller than usual rise in clothing prices, and falling motor fuel prices, were the main contributors to the drop in the rate.

There was also a fall in the price of household gas.

Business correspondent Aaron Heslehurst looks at what the fall means and why it matters.