You can use DLLs with Dexterity applications to perform tasks that extend the capability of the Dexterity development system. They can provide capabilities such as performing special calculations or allowing Dexterity applications to communicate with peripheral hardware. For example, if you were using Dexterity to write a point-of-sale application, you would probably need to communicate with a cash register. Because Dexterity doesn’t provide this capability, you could use a DLL to add this functionality.