The ukulele is a four-stringed instrument that has its origins in Portugal, but was adapted by Hawaiians in the 19th Century. Its size can vary, with the larger instruments producing deeper tones. The ukulele became particularly popular in Hawaii during the reign of King Kalākaua, who incorporated the instrument into performances at official state gatherings. It was later used in recordings by artists such as Bing Crosby and Elvis Presley. National Ukulele Day takes place on February 2, when ukulele players from around the country will strum their favorite tunes to celebrate.