Basically, an executive order is an official statement from the president about how the federal agencies he oversees are to use their resources.

It falls under the broader umbrella of “executive actions,” which derive their power from Article II of the Constitution, and it is the most formal executive action. Executive actions also include presidential memorandums (which are a step below executive orders and basically outline the administration’s position on a policy issue), proclamations and directives.

An executive order is not the president creating new law or appropriating new money from the U.S. Treasury — both things that are the domain of Congress; it is the president instructing the government how it is to work within the parameters that are already set by Congress and the Constitution.

Trump’s executive order on building a border wall , for example, basically establishes building the wall as a federal priority and directs the Department of Homeland Security to use already-available funding to get the ball rolling on its construction.

The president’s executive orders are recorded in the Federal Register and are considered binding, but they are subject to legal review.