As merchandisers gained the ability to record transaction data, they started collecting and analyzing data about consumer behavior.The term data mining is used to describe the collection of analysis techniques used to infer rules from or build models from large data sets. One of the best-known examples of data mining in commerce is the discovery of association rules relationships between items that indicate a relationship between the purchase of one item and the purchase of another. These rules can help a merchandiser arrange products so that, for example, a consumer purchasing ketchup sees relish nearby. More sophisticated temporal data mining may suggest that a consumer who buys a new charcoal grill today is likely to buy a fire extinguisher in the next month.