The term is most strongly associated with traditional consumer loans, originated and serviced locally, and repaid over time by regular payments of principal and interest.
In 2007 the US Department of Defense exempted installment loans from legislation designed to prohibit predatory lending to service personnel and their families, acknowledging in its report[2] the need to protect access to beneficial installment credit while closing down less safe forms of credit.
(From the Fordham University Internet Ancient History Sourcebook, Editor: Paul Halsall, "A Collection of Contracts from Mesopotamia, c. 2300 - 428 BCE").
A type of installment contract other than a loan involves the purchase of durable goods on credit.
It opened in New York City and soon began extending credit for purchases of furniture items with payment by installments.