A fixed rate mortgage is one where the interest rate stays the same for an agreed period of time – this is usually two, three, five, seven or ten years. So even if other interest rates go up or down during that time, your interest rate won’t change.
A variable rate mortgage is one where the interest rates can go up or down, meaning your repayments may also go up and down. Rate changes can happen for a variety of reasons - some will be decided by your lender, others might be driven by what’s happening in the economy. Sometimes variable rate mortgages may be subject to a "floor" (below which the rate can never fall), or a "ceiling" (which the rate cannot go above).
Read our different types of mortgages article to discover what others are available.