A revolving line of credit is a type of credit facility that does not have a fixed number of payments, in contrast to installment credit (such as home mortgages, automobile loans, and student loans).  Examples of revolving credits used by consumers include traditional credit cards.  Corporate revolving credit facilities are typically used to provide liquidity for a company's day-to-day operations.

Typical characteristics of a Revolving line of credit include: 

• The borrower may use or withdraw funds up to a pre-approved credit limit.
• The amount of available credit decreases and increases as funds are borrowed and then repaid.
• The credit may be used repeatedly.
• The borrower makes payments based only on the amount they've actually used or withdrawn, plus interest.
• The borrower may repay over time (subject to any minimum payment requirement), or in full at any time.
• In some cases, the borrower is required to pay a fee to the lender for any money that is undrawn on the revolver; this is especially true of corporate bank loan revolving credit facilities.¹

¹ http://en.wikipedia.org/wiki/Revolving_credit

Traditional credit card system of payment issued to users of a specified banking system.   Credit cards are typically offered by a banking or financing facility (e.g. Chase or Bank of America).  A credit card is different to a debit card in that it does not remove money from the user's account after every transaction.  In the case of credit cards, the issuer lends money to the consumer (or the user) to be paid to the merchant.  It is also different from a charge card (though this name is sometimes used by the public to describe credit cards), which requires the balance to be paid in full each month.  In contrast, a credit card allows the consumer to 'revolve' their balance, at the cost of having interest charged.

A Home Equity Line of Credit (HELOC) is a loan in which the lender agrees to lend a maximum amount within an agreed period (called a term), where the collateral is the borrower's equity in his/her house.

A HELOC differs from a conventional home equity loan in that the borrower is not advanced the entire sum up front, but uses the line of credit to borrow sums that total no more than the amount, similar to a credit card. At closing you are assigned a specified credit limit that you can borrow up to. During a "draw period" (typically 5 to 25 years), HELOC funds can be borrowed and you pay back only what you use plus interest. Depending on how much you use the HELOC, you will have a minimum monthly payment requirement (often "interest only"); beyond the minimum, it is up to you how much to pay and when to pay. At the end of the draw period, you will have to pay back the full principal amount borrowed either in a lump-sum balloon payment or according to a loan amortization schedule.

Another important difference from a conventional loan: the interest rate on a HELOC is variable based on an index such as prime rate. This means that the interest rate can - and almost certainly will - change over time. Homeowners shopping for a HELOC must be aware that not all lenders calculate the margin the same way. The margin is the difference between the prime rate and the interest rate the borrower will actually pay. Lenders do not generally offer this information and it is up to the consumer to ask for it before taking a loan.

HELOC loans have become very popular in the United States in the 2000s, in part because interest paid is typically (depending on specific circumstances) deductible under federal and many state income tax laws. This effectively reduces the cost of borrowing funds. Another reason for the popularity of HELOCs is the flexibility not found in most other loans - both in terms of borrowing and repaying on a schedule determined by the borrower. Furthermore, HELOC loans' popularity growth may also stem from their having a better image than a "second mortgage," a term which can more directly imply an undesirable level of debt.

It must always be kept in mind that the underlying collateral of a home equity line of credit (HELOC) is the home. This means that failure to repay the loan or meet loan requirements may result in foreclosure.

As an example of a Healthcare Line of Credit, Heathcare Creditline^® has been helping patients pay their healthcare providers' bills since 1985. Healthcare Creditline offers consumers immediate access to credit for their healthcare needs. It is designed to take care of a family's healthcare expenses, and you can save your bankcard credit for day-to-day purchases. Consumers with health insurance can use their Healthcare Creditline card to pay co-payments and deductibles.

If approved qualified patients can charge their treatment, and take time to pay by making small minimum monthly payments. This convenience allows time to adjust their budget or file for insurance reimbursements. No annual fee and minimum payments start as low as $10.00 per month. There is no cost to apply, and no annual fee.

Revolving lines of credit give consumers and corporations day-to-day liquidity and aid in cash flow financing. The flexibility in contract tenor and payment amounts allows consumers to finance the unexpected or the unaffordable. Banks that lend revolving line of credit attract consumers with their flexibility and profit from the costs associated with providing this credit (interest rates, annual fees, etc).

• Smoothing the Vicissitudes
• Revolving lines of credit allow consumers to finance expenses over time with some flexibility in payment amounts and contract tenor.  However, this flexibility often comes at a cost – higher interest rates, annual fees, etc.