A mortgage loan is a loan secured by real property through the use of a note which evidences the existence of the loan and the encumbrance of that realty through the granting of a mortgage which secures the loan. However, the word mortgage alone, in everyday usage, is most often used to mean mortgage loan.

A home buyer or builder can obtain financing (a loan) either to purchase or secure against the property from a financial institution, such as a bank, either directly or indirectly through intermediaries. Features of mortgage loans such as the size of the loan, maturity of the loan, interest rate, method of paying off the loan, and other characteristics can vary considerably.

Basic concepts and legal regulation

According to Anglo-American property law, a mortgage occurs when an owner (usually of a fee simple interest in realty) pledges his interest as security or collateral for a loan. Therefore, a mortgage is an encumbrance on property just as an easement would be, but because most mortgages occur as a condition for new loan money, the word mortgage has become the generic term for a loan secured by such real property.

As with other types of loans, mortgages have an interest rate and are scheduled to amortize over a set period of time; typically 30 years. All types of real property can, and usually are, secured with a mortgage and bear an interest rate that is supposed to reflect the lender's risk.

Mortgage lending is the primary mechanism used in many countries to finance private ownership of residential property. For commercial mortgages see the separate article. Although the terminology and precise forms will differ from country to country, the basic components tend to be similar:

• Property: the physical residence being financed. The exact form of ownership will vary from country to country, and may restrict the types of lending that are possible.
• Mortgage: the security created on the property by the lender, which will usually include certain restrictions on the use or disposal of the property (such as paying any outstanding debt before selling the property).
• Borrower: the person borrowing who either has or is creating an ownership interest in the property.
• Lender: any lender, but usually a bank or other financial institution.
• Principal: the original size of the loan, which may or may not include certain other costs; as any principal is repaid, the principal will go down in size.
• Interest: a financial charge for use of the lender's money.
• Foreclosure or repossession: the possibility that the lender has to foreclose, repossess or seize the property under certain circumstances is essential to a mortgage loan; without this aspect, the loan is arguably no different from any other type of loan.

Many other specific characteristics are common to many markets, but the above are the essential features. Governments usually regulate many aspects of mortgage lending, either directly (through legal requirements, for example) or indirectly (through regulation of the participants or the financial markets, such as the banking industry), and often through state intervention (direct lending by the government, by state-owned banks, or sponsorship of various entities). Other aspects that define a specific mortgage market may be regional, historical, or driven by specific characteristics of the legal or financial system.