An interest-only mortgage allows you to pay only the interest charges on your loan each month, without any portion going towards the original borrowed capital. This means your monthly payments are lower compared to a repayment mortgage.
At the end of the mortgage term, you will still owe the initial borrowed amount to the lender. You will only have paid the interest, meaning you will still have the initial amount left to pay.
Typically, this outstanding balance needs to be paid as a lump sum.