Points of sale (POS) systems are electronic systems that provide businesses with the capability to retain and analyze a wide variety of inventory and transaction data on a continuous basis. POS systems have been touted as valuable tools for a wide variety of business purposes, including refining target marketing strategies; tracking supplier purchases; determining customer purchasing patterns; analyzing sales (on a daily, monthly, or annual basis) of each inventory item, department, or supplier; and creating reports for use in making purchases, reorders, etc. Basic point of sale systems currently in use includes standalone electronic cash registers, also known as ECRs; ECR-based network systems; and controller-based systems. All function essentially as sales and cash management tools, but each has features that are unique.

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Standalone ECRs
These electronic registers operate independently of one another, and are thus the most limited of the three POS system types.
Network Systems
Network or ECR-based point-of-sale systems feature multiple terminals arranged into a primary/secondary configuration.
Controller-Based POS System
The top POS systems are controller-based systems in which each terminal is connected to a computer the “controller” of the system which receives and stores all sales, merchandise, and credit data.