Barack Obama was the President of the United States from 2009 to 2017. He was a well respected president. The average person would be nervous to meet the President, and Jimmy Fallon was very nervous, so he wanted to dress well. He wore a suit to the White house, even though it was July and the weather was hot.
Watching Jimmy Fallon interviews are a great way to learn English. His interview style is fun and not too serious. He has extremely popular guests on, so it is also a great way to learn about American pop-culture. The guests usually tell funny and interesting stories.