The Duke and Duchess of Cambridge welcome a baby boy.

The great Kate wait is over! On July 22, Monday afternoon, the Duke and Duchess of Cambridge welcomed their baby boy, with the rest of the world cheering them on.

Congratulations to Kate & William on the birth of their baby boy! So relieved that his name won’t include the words Ivy or Apple.

— Joan Rivers (@Joan_Rivers) July 22, 2013

Celebrities were just as joyous over the news that Kate Middleton finally gave birth. Tweets rushed in, from excited well-wishers to baby name detectives. Congratulations with a touch of humour came courtesy of talk show host Ellen DeGeneres who said, "It's a boy! So happy for my cousin Kate and and the future King of England!" Ellen once received a letter from the New England Genealogical Society stating that she and Kate Middleton are in fact, distant cousins. Television presenter Vernon Kay joined the fun, sharing, "Congratulations William and Kate :-) See you at Jungle mania, summer camp, Legoland, kids club and ToysRUs very soon.X." "E! Fashion Police's" Joan Rivers could not resist celebrity baby name jokes, which she tweeted at the expense of Beyonce and Gwyneth Paltrow. The comedienne wrote, "Congratulations to William & Kate on the birth of their baby boy! So relieved that his name won't include the words Ivy or Apple."

Jack Osbourne, who welcomed baby girl Pearl Clementine in 2012, said, "EPIC!!!! A new prince was born. Its like real life Game of Thrones #royal baby." The Saturdays singer Rochelle Humes was just as thrilled about William and Kate's baby boy, who is third in line to the throne. She wrote, "A future King...a little baby boy. How exciting x."

Singers Cheryl Cole and Katherine Jenkins shared their happiness, with Katherine trying to get a few hashtags trending. Cheryl tweeted, "Congratulations to William and Kate!! So happy they have a healthy baby and everyone is good..." The Welsh mezzo-soprano wrote, "Awwww... It's a boy! Congratulations! Soo happy for you! #GlassesRaised #Toast #Celebrations."

The great Kate wait may be over with royal baby watchers finally getting their hands on some information about Kate and William's baby, but, with the little prince's name still unknown, this next obsession will surely keep Twitter busy!