The most common reason for refinancing is to save money. By obtaining a lower interest rate that causes one's monthly mortgage payment to be reduced. By reducing the term of the loan, thus saving money over the life of the loan.
People also refinance to convert their adjustable loan to a fixed loan.
The main reason behind this type of refinance is to obtain the stability and the security of a fixed loan. Fixed loans are very popular when interest rates are low, whereas adjustable loans tend to be more popular when rates are higher. When rates are low, homeowners refinance to lock in low rates. When rates are high, homeowners prefer adjustable loans to obtain lower payments. The loans being consolidated may include second mortgages, credit lines, student loans, credit cards, etc.