Interest is basically where the bank pays you for putting your money in one of their accounts. If you open a savers account in a bank and you put in £20, you will get about £1 every year for saving with them.
It means that they are getting less money for deferring expenditure and saving instead. However, it is not the low nominal interest rates which matter but what the "real" interest rates are. This is the difference between the nominal interest rate and the rate of inflation. An interest rate of 2% when inflation is 0% is good news for savers but an inflation rate even as high as 10% is bad news if inflation is higher than 10%.
The three ways money is transferred from savers to businesses
good money savers, conservative spenders
To make money.
An interest rate is the amount of money a bank can charge on the loan that they provide you. That is how they make their profit. If they didn't charge an interest rate and just loaned out money, then there's no way they can make money off of the loan.
Money is channeled through financial institutions such as banks. A saver saving with a bank account seeks to keep the money in the bank as it earns him interest. A borrower in need of a loan applies for a loan at the bank and if he is eligible, gets the loan at an interest rate. The borrower may chose to use the funds to invest in a business venture and thus be becomes an investor.
This is how you make money on the bonds. You will put in the money and will receive that money and the interest on it at the end of the term.
Transferring money from savers to spenders
Banks make money by lending money to people and charging people for borrowing. The amount banks charge is called interest. Banks borrow money from other people and pay them interest on the amount borrowed. Banks charge more interest on the money they lend than they pay one the money they borrow. That is how they make money. When people deposit money with a bank, the bank is literally borrowing money from some people so they can lend it to other people. That is why banks pay interest.
Banks make money by loaning out money that has been deposited in the bank and charging interest on it. They are limited as to how much money they can loan by how much money has been deposited in the bank. To encourage people to deposit money in the bank they offer to pay some interest on the deposits. The interest paid on the deposits is less than what they charge people who borrow that money. For example: they might pay 1% annual interest on a deposit of $100,000 - which will cost them $1,000. While that money is on deposit, they loan out $80,000 of it at 5% interest - which makes them $4,000 - for a profit of $3,000. They interest they pay to their customers is an inducement for them to make deposits so that they have more money to loan out and thus can make more money.
Interest is the money banks get in exchange for lending money. The more "safe" loans they make, the more money they make. This helps keep bank investors happy. A loan at 0% offers the bank zero incentive for lending money.