end user - a person who uses a product or service on a computer "Developers must maintain a close relationship with end users if they want to have a successful career."

error --an incorrect action attributable to poor judgment, ignorance, or inattention "The computer reported a "division by zero" error and automatically aborted the program."

 execute-to start a program on a computer "The program was set to execute every night at midnight."

open source --a program in which the code is distributed allowing programmers to alter and change the original software as much as they like "The article stated that many programmers prefer open source solutions because they can modify features and fix bugs without waiting for an upgrade or patch from the manufacturer."

 proprietary-- privately developed and owned technology "Because of proprietary code, you may not modify or redistribute the source code of Windows or Macintosh operating systems."