The issue of mortgage loans and real estate financing is very important in real estate investing because, in most cases, it is the key for making a transaction feasible and/or profitable (see the article below titled "Using Borrowed Funds to Finance Property Investments").

Furthermore, most of the time, borrowing
a significant part of the capital required to purchase a property is the key in achieving double-digit returns. Of course, not in all cases borrowing will enhance returns and make an investment more profitable. The main sources of property loans are conventional or non-conventional mortgage lenders and brokers. The article below explains a simplistic technique in assessing whether using borrowed funds to finance a particular property investment will enhance investment returns.
Mortgages may differ in several dimensions, including their priority in claiming the property in case of default (first mortgages, second mortgages, etc.), interest rate structure (fixed rate or adjustable-rate), the level of the interest rate charged, the extent to which the loan is amortized, etc. See
this article for a more detailed discussion of the different types of mortgages.