It's measured by a percentage or rate.

The most important interest rate, one that affects the whole economy, is set by a country's central bank.

It's called the base rate.

Central banks lend money to commercial banks, who in turn lead to businesses and individuals.

Of course, they charge interest on those loans.

The theory and the hope is that these loans lead to more spending and investment and a healthy economy.

When a central bank cuts its base rate, it becomes less attractive to save.

On the other hand, businesses are more likely to borrow money to invest in new machinery.

War Take on more staff People feel more confident about taking out a mortgage on a new home or buying a new car to boost a sluggish economy of central bank may even introduce a negative interest rate to try to get lenders to invest in the real economy rather than hoard cash.

But let's not forget that the main task of any central bank is to provide a framework for the economy to grow sustainably by targeting a steady currency and low inflation.

So if for example, prices are rising too fast.

The central bank may want to intervene to cool the economy by pushing interest rates up.

This would encourage people to save.

They tend to spend less on consumer goods.

Companies may think twice about splashing out on new equipment, and retailers might cut prices to encourage trade.

This, in turn, can calm inflation.

However, people with say a mortgage on a house would suffer their monthly repayments would increase, so high or low interest rates have an impact on all of us.