This is the most common loan, where the interest rate can vary with official interest rates, but are ultimately determined by the lender. They typically have redraw facilities and offset accounts that give them flexibility. Many lenders will consider a discount or honeymoon rate based upon the size or initial nature of the borrowing.
They can be refinanced with another lender, some loans without exit costs. The interest rates do vary and, unlike a fixed interest loan, the borrower will also experience different repayment rates over the life of the loan.