The part about jurisdiction creates a very narrow exception that today essentially applies only to children of accredited foreign diplomats. Other than that, the citizenship or immigration status of a person’s parents has not been held to have any effect on this right.

(The term “birthright citizenship” can also refer to another way a person can be born an American citizen: By having a citizen parent. This source of citizenship, created by federal law rather than directly by the Constitution, has not generally figured in the debate over illegal immigration, though it comes up sometimes in presidential elections. )

Can the president abolish it?

No. The president cannot amend the Constitution, and an executive order trying to end or restrict the right to citizenship of persons born in the United States would almost certainly be challenged in court as a violation of the 14th Amendment.

Mr. Trump has raised the abolition idea before, and some of his allies have suggested that the jurisdiction language in the amendment could be construed to exclude children of undocumented immigrants. But the overwhelming consensus of legal experts is that such an argument would have no chance of prevailing in court.

Do other countries have the same policy?

Those in the Western Hemisphere generally do, according to a 2010 study, while those in the rest of the world generally do not, at least with regard to people who are not legal residents. Several countries that, like the United States, had traditions of universal birthright citizenship rooted in English common law, including Britain, Ireland, Australia, New Zealand and India, have restricted or abolished the right in recent decades.