The point of sale (POS), or point of purchase (POP), is the time and place at which a retail transaction is completed. At the point of sale, the merchant calculates the amount owed by the customer, indicates that amount, may prepare an invoice for the customer (which may be a cash register printout), and indicates the options for the customer to make payment. It is also the point at which a customer makes a payment to the merchant in exchange for goods or after provision of a service. After receiving payment, the merchant may issue a receipt, as proof of transaction, which is usually printed but can also be dispensed with or sent electronically.

To calculate the amount owed by a customer, the merchant may use various devices such as weighing scales, barcode scanners, and cash registers (or the more advanced "POS cash registers", which are sometimes also called "POS systems"). To make a payment, payment terminals, touch screens, and other hardware and software options are available.

The point of sale is often referred to as the point of service because it is not just a point of sale but also a point of return or customer order. POS terminal software may also include features for additional functionality, such as inventory management, CRM, financials, or warehousing.

Businesses are increasingly adopting POS systems, and one of the most obvious and compelling reasons is that a POS system eliminates the need for price tags. Selling prices are linked to the product code of an item when adding stock, so the cashier merely scans this code to process a sale. If there is a price change, this can also be easily done through the inventory window. Other advantages include the ability to implement various types of discounts, a loyalty scheme for customers, and more efficient stock control. These features are typical of almost all modern ePOS systems.

Terminology

Retailers and marketers will often refer to the area around the checkout instead as the point of purchase (POP) when they are discussing it from the customer's perspective. This is particularly the case when planning and designing the area as well as when considering a marketing strategy and offers.

Some point of sale vendors refer to their POS system as "retail management system" which is a more appropriate term, since this software is not just for processing sales but comes with many other capabilities, such as inventory management, membership systems, supplier records, bookkeeping, issuing of purchase orders, quotations and stock transfers, hide barcode label creation, sale reporting and in some cases remote outlet networking or linkage, to name some major ones.

Nevertheless, it is the term POS system rather than retail management system that is in vogue among both end-users and vendors.

The basic, fundamental definition of a POS System is a system which allows the processing and recording of transactions between a company and its consumers, at the time in which goods and/or services are purchased.

History

Software before the 1990s

Early electronic cash registers (ECR) were controlled with proprietary software and were limited in function and communication capability. In August 1973, IBM released the IBM 3650 and 3660 store systems that were, in essence, a mainframe computer used as a store controller that could control up to 128 IBM 3653/3663 point of sale registers. This system was the first commercial use of client-server technology, peer-to-peer communications, local area network (LAN) simultaneous backup, and remote initialization. By mid-1974, it was installed in Pathmark stores in New Jersey and Dillard's department stores.

One of the first microprocessor-controlled cash register systems was built by William Brobeck and Associates in 1974, for McDonald's Restaurants. It used the Intel 8008, an early microprocessor (forerunner to the Intel 8088 processor used in the original IBM Personal Computer). Each station in the restaurant had its own device which displayed the entire order for a customer — for example, Vanilla Shake, Large Fries, Big Mac — using numeric keys and a button for every menu item. By pressing the [Grill] button, a second or third order could be worked on while the first transaction was in progress. When the customer was ready to pay, the [Total] button would calculate the bill, including sales tax for almost any jurisdiction in the United States. This made it accurate for McDonald's and very convenient for the servers and provided the restaurant owner with a check on the amount that should be in the cash drawers. Up to eight devices were connected to one of two interconnected computers so that printed reports, prices, and taxes could be handled from any desired device by putting it into Manager Mode. In addition to the error-correcting memory, accuracy was enhanced by having three copies of all important data with many numbers stored only as multiples of 3. Should one computer fail, the other could handle the entire store.

In 1986, Gene Mosher introduced the first graphical point of sale software featuring a touchscreen interface under the ViewTouch trademark on the 16-bit Atari 520ST color computer. It featured a color touchscreen widget-driven interface that allowed configuration of widgets representing menu items without low level programming.The ViewTouch restaurant system by Giselle Bisson The ViewTouch point of sale software was first demonstrated in public at Fall Comdex, 1986, in Las Vegas, Nevada, to large crowds visiting the Atari Computer booth. This was the first commercially available POS system with a widget-driven color graphic touch screen interface and was installed in several restaurants in the US and Canada.

In 1986, IBM introduced its 468x series of POS equipment based on Digital Research's Concurrent DOS 286 and FlexOS 1.xx, a modular real-time multi-tasking multi-user operating system.

Modern software (post-1990s) A wide range of POS applications have been developed on platforms such as Windows and Unix. The availability of local processing power, local data storage, networking, and graphical user interface made it possible to develop flexible and highly functional POS systems. Cost of such systems has also declined, as all the components can now be purchased off-the-shelf.

In 1993, IBM adopted FlexOS 2.32 as the basis of their IBM 4690 OS in their 469x series of POS terminals. This was developed up to 2014 when it was sold to Toshiba, who continued to support it up to at least 2017.

With increased options for commodity hardware and a more competitive market, the 1990s saw increased attention paid to the user interaction between store employees and POS systems. Touchscreens and larger displays became widely available in the 1990s, offering an alternative to limited displays like two-line VFDs used in the IBM 4683. The performance of the employees using the POS devices, a controllable cost for the business, depends upon the ease of learning, ease of use, and level of employee experience with it. Although experienced employees work more quickly with mechanically keyed entry, some systems favoured adopting GUI technology for ease of learning or for ergonomic factors.

The key requirements that must be met by modern POS systems include high and consistent operating speed, reliability, ease of use, remote supportability, low cost, and rich functionality. Retailers can reasonably expect to acquire such systems (including hardware) for about US$4000 (as of 2009) per checkout lane.

Reliability depends not wholly on the developer but at times on the compatibility between a database and an OS version. For example, the widely used Microsoft Access database system had a compatibility issue when Windows XP machines were updated to a newer version of Windows. Microsoft offered no immediate solution. Some businesses were severely disrupted in the process, and many downgraded back to Windows XP for a quick resolution. Other companies utilized community support, for a registry tweak solution has been found for this.

POS systems are one of the most complex software systems available because of the features that are required by different end users. Many POS systems are software suites that include sale, inventory, stock counting, vendor ordering, customer loyalty and reporting modules. Sometimes purchase ordering, stock transferring, quotation issuing, barcode creating, bookkeeping or even accounting capabilities are included. Each of these modules is interlinked if they are to serve their practical purpose and maximize their usability.

For instance, the sale window is immediately updated on a new member entry through the membership window because of this interlinking. Similarly, when a sale transaction is made, any purchase by a member is on record for the membership window to report providing information like payment type, goods purchased, date of purchase and points accumulated. Comprehensive analysis performed by a POS machine may need to process several qualities about a single product, like selling price, balance, average cost, quantity sold, description and department. Highly complex programming is involved (and possibly considerable computer resources) to generate such extensive analyses.

POS systems are designed not only to serve the retail, wholesale and hospitality industries as historically is the case. Currently POS systems are also used in goods and property leasing businesses, equipment repair shops, healthcare management, ticketing offices such as cinemas and sports facilities and many other operations where capabilities such as the following are required: processing monetary transactions, allocation and scheduling of facilities, keeping record and scheduling services rendered to customers, tracking of goods and processes (repair or manufacture), invoicing and tracking of debts and outstanding payments.

Different customers have different expectations within each trade. The reporting functionality alone is subject to so many demands, especially from those in the retail/wholesale industry. To cite special requirements, some business's goods may include perishables and hence the inventory system must be capable of prompting the admin and cashier on expiring or expired products. Some retail businesses require the system to store credit for their customers, credit which can be used subsequently to pay for goods. A few companies expect the POS system to behave like a full-fledged inventory management system, including the ability to provide FIFO (First In, First Out) and LIFO (Last In, First Out), reports of their goods for accounting and tax purposes.

In the hospitality industry, POS system capabilities can also diverge significantly. For instance, a restaurant is typically concerned about how the sale window functions: whether it has functionality such as creating item buttons, various discounts, adding a service charge, holding of receipts, queuing, table service as well as takeaways, merging and splitting of a receipt. These capabilities may be insufficient for a spa or slimming center which would require, in addition, a scheduling window with historical records of customers' attendance and their special requirements.