A BusinessRule (in a programming context) is knowledge that gets applied to a set of data to create new value.  Or it may be a rule about how to create, modify, or remove data.  Or perhaps it is a rule that specifies when certain processes occur.

For example, we have a rule about email addresses -- when the Driver Name field on our object identifier changes, we erase the email address.  When we receive a new email address, we make sure that it contains an "@" sign and a valid domain not on our blacklist.

Many BusinessRules can be categorized.  For example:

Data-Related

''We get data from vendor A and validate it against our database, setting ...''

Setup-Related

''We require all new customers to supply us with the following information ...''

Product-Offering-Related

''Our Preferred customers in France can select from the following options...''

Process-Control-Related

''Widgets have to pass through these five quality control points before being released to the warehouse...''

Business-Related

''After working for us for five years you are eligible for semi-annual enrollment in ...''

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See also: BusinessRequirements BusinessRules