Donald Trump has signed more than a hundred executive orders since taking office on policies covering immigration, health care, abortion and trade. But what exactly do they mean? Is there a difference between an executive order and an executive action? And how does Trump compare to other presidents when it comes to the pace of these early edicts? We break it all down below:

What is an executive order?

An executive order is a specific type of presidential action — an official, legally binding mandate passed down from the president to federal agencies under the executive branch. Executive orders are printed in the Federal Register, and they’re numbered consecutively for the sake of keeping them straight. Essentially, an executive order gives agencies instructions on how to interpret and carry out federal law.

Is an order different from an executive action?

Not exactly. “Executive action” is a catch-all term that describes any action taken by a president. So technically, an executive order is one type of executive action. Other common types include presidential memorandums and proclamations, which are also used to direct the operations of the executive branch.

What about memorandums and proclamations?

An executive memorandum is essentially an executive order. The difference: An executive memorandum does not have an established process for how the president issues it. Memoranda do not have to be submitted to the Federal Register and are therefore harder to track. President Barack Obama utilized executive memorandum at least 407 times, including on DACA (the immigration policy), gun control and the overtime rule. President Trump has used this type of executive action a number of times as well, to impose tariffs on China, tighten asylum laws and withdraw from the Trans-Pacific Partnership, among others efforts.

Proclamations are the last form of executive actions. These are largely used for ceremonial purposes and usually don’t carry any legal effect. For example, when a former justice of the Supreme Court dies, a president might issue a proclamation, ordering American flags to be flown at half-staff.

Are these things spelled out in the Constitution?

Yes and no. You won’t find the term “executive order” in the Constitution. In the early days of the republic, presidents generally issued executive orders as a way to keep the public in the loop, not to direct policy.

Instead, the so-called “power of the pen” comes from the “vesting clause” of the Constitution. That clause grants the president “executive power” — an extremely vague term that, historically, has come to mean all the complicated administrative actions associated with the day-to-day operations of the government.

Among the most prolific with the pen: Franklin D. Roosevelt, who wrote 3,721 executive orders.

As a result, there has always been a debate about executive power, how the founder envisioned its use, and what it means for presidents in the modern era. Constitutional experts generally agree that executive actions are legal as long as the president has authority in the policy area, and those policies are a reasonable interpretation of court precedent.

Is Trump on pace to issue more executive orders more than past presidents?

Every president (with the exception of William Henry Harrison, who died of pneumonia 32 days into his term, in 1841) has issued an executive order, according to an analysis from the National Archives and The American Presidency Project at the University of California, Santa Barbara.

Among the most prolific with the pen: Franklin D. Roosevelt, who wrote 3,721 executive orders; Woodrow Wilson, with 1,803; and Calvin Coolidge, with 1,203.

Meanwhile, John Adams, James Madison and James Monroe issued just one during their presidencies, while John Quincy Adams only wrote three.

More recently, Ronald Reagan issued 381 executive orders. Bill Clinton issued 364, and George W. Bush issued 291. Barack Obama issued 277 executive orders, or an average of 35 per year.

As of Thursday, President Trump had issued 114 executive orders in his two and a half years in office, or an average of 45 per year. At that pace, he would beat out Obama and George W. Bush if elected to another four-year term, but would fall far short of the records set by Roosevelt.

Does the number of orders actually matter?

It depends. Experts on executive power like to point that quantity isn’t everything. Some orders carry less weight, while others are far-reaching. Counting them is important, but ultimately the proof is in the pudding. A few major executive orders can outweigh dozens of smaller ones.

Rachel Wellford contributed to this report.

Correction: This story has been updated to reflect that Obama signed an average of 35 executive orders per year.