President Trump had barely reacquainted himself with the Oval Office after his second inauguration when he began shredding the D.E.I. initiatives of the Biden administration, fulfilling a cause célèbre for conservatives that had helped power his political comeback.

On his second day back in power, Mr. Trump ordered that agency heads place those officials who had been responsible for overseeing diversity, equity and inclusion programs in the federal government on paid administrative leave and that their offices be shuttered.

Part of an executive action signed one day earlier, it was the first step in rolling back the D.E.I. policies that had been a hallmark of the administration of his Democratic predecessor, President Joseph R. Biden Jr.

This is how we got here:

What is D.E.I.?

D.E.I. stands for diversity, equity and inclusion. A page on the U.S. Department of Labor website, which was removed two days into the president’s new term, defined diversity as acknowledging all the ways that people differ. That can include race, sex, gender, age, sexual orientation, disability, socioeconomic status, religious beliefs and more.

“Organizations that respect diversity can come up with new ideas, solve problems, grow and run more efficiently,” the deleted entry on D.E.I. read on the agency’s website, which later read, “Page not found.”

It’s not new

While the three-letter abbreviation has become a hot topic in recent years, the principle has been around for decades in both the public and the private sectors. It developed as a result of the Civil Rights Act of 1964, which prohibited employment discrimination based on race, color, religion, sex or national origin.