U.S. — Birthright citizenship is defined as a constitutional right for any child born in the United States to automatically gain U.S. citizenship.
The 14th Amendment states that "All persons born or naturalized in the United States, and subject to the jurisdiction thereof, are citizens of the United States and of the State wherein they reside."
The amendment was ratified in 1868 to guarantee citizenship for all. This included former slaves, who at the time didn't have the right to own property, roam freely or even stay in the country.
However, it was still never clearly defined whether or not children born of immigrants in the U.S. were automatically U.S. citizens.
Then came the case of Wong Kim Ark. Wong was the son of Chinese immigrants and was born in California. After he returned from a trip to China in 1895, the federal government tried to stop him from re-entering the U.S. under the Chinese Exclusion Act.
His case ended up in court, and after a years-long battle, the Supreme Court in 1898 ruled that Wong was in fact a U.S. citizen, as he was born in the U.S.
Meanwhile, despite all this, Native Americans were still consistently denied rights given to others born in the U.S. until Congress finally granted citizenship to all Native Americans in 1924.
President Donald Trump has announced plans to issue an Executive order to end birthright citizenship, the Supreme Court would still have the power to overturn the Executive order and interpret the Constitution on its own.
Other than the U.S., there are 30 other nations in the world that recognize birthright citizenship including Argentina, Brazil, Canada, Panama and Mexico.