An Engineering Change Order (ECO) is a formal request to make changes in the design of an engineering project, product, or system. It’s typically issued by the customer or stakeholder and defines the changes needed, who will be impacted by them, and the costs associated with making these changes. ECOs are used to document changes so that all stakeholders are clear on the project’s objectives and timeline. In addition, they provide an important reference point throughout the course of the project, safeguard against costly mistakes, and help to ensure that all parties are on the same page when it comes to desired outcomes.