There are several types of loan modifications. 

There is a loan modification which may lower an interest rate temporarily allowing a homeowner to maintain their home with a lower monthly payment. 

There is another type of loan modification, where the loan is converted into an amortized loan with a fixed monthly payment for the remainder of the loan.

There is a loan modification where a homeowner may be able to get a principle write down.  The FHA Secure program allows this type of a loan modification, however very few homeowners will qualify.

There is another loan modification where a homeowner may be able to get a principle write down should there be a TILA Violation and has Legal Representation to negotiate with the lender.

Finally, there are some cases, where a Bankruptcy Strategy may help a homeowner obtain a loan modification.