A payday loan (also called a paycheck advance or payday advance) is a small, short-term loan that is intended to cover a borrower's expenses until his or her next payday. The loans are also sometimes referred to as cash advances, though that term can also refer to cash provided against a prearranged line of credit such as a credit card (see cash advance). Legislation regarding payday loans varies widely between different countries and, within the USA, between different states.

Some jurisdictions impose strict usury limits, limiting the nominal annual percentage rate (APR) that any lender, including payday lenders, can charge; some outlaw payday lending entirely; and some have very few restrictions on payday lenders. Due to the extremely short-term nature of payday loans, the difference between APR and effective annual rate (EAR) can be substantial, because EAR takes compounding into account. For a $15 charge on a $100 2-week payday loan, the APR is 26 × 15% = 390% but the EAR is (1.1526 − 1) × 100% = 3,685%. Careful reporting of whether EAR or APR is quoted is necessary to make meaningful comparisons.

工资日贷款”，或者叫做高利贷

工资日贷款是一种小额、短期贷款，用于贷款人下一次发薪之前临时急用所需（因此还款日期也就是下次发薪之时）。这种贷款额额度往往在100美元到1500美元之间，通常还款期限是2周，通常年利率在390%到780%。也就是说，每贷款100美元，按期还款的时候（一般是两周左右）需要缴付的利息是15到30美元。

“工资日贷款”发放人（高利贷商人）指出：这种贷款形式往往是那些拥有不良信用记录的消费者唯一的贷款来源，因为拥有不良信用记录的消费者一般是无法得到银行贷款、信用卡或其他方式的低息贷款。对高利贷持批评意见的人认为：绝大多数贷款人在还款日到来的时候发现自己处于比贷款前更糟糕的财务状况，以至于他们不得不陷入循环贷款的圈套。

维基百科对“工资日贷款”有如下概括：

在美国，“工资日贷款”行业一年的放贷额在2001年是80亿美元到140亿美元之间，2006年则超过280亿美元。

“工资日贷款”公司91%的收入来源于那些不能一次及时付清贷款的贷款人。

只有1%的贷款人能够一次及时付清贷款（在每年只贷一次款的情况下）。

典型的情况是：贷款人贷款325美元后，还款时（由于无法及时付清贷款导致累计）需要还793美元。