Oil is a fuel that ships carry around the world. A barrel is a big drum of oil. On Friday, one barrel cost about $114.50. Later it cost $117.20.
Oil costs more because of fighting near Saudi Arabia. A group from Yemen, called the Houthis, said they hit places there, including airports. A big oil company moved its workers out of one office.
Saudi Arabia sells a lot of oil. When it is harder to get, oil costs more. Oil has cost more for three weeks in a row.