Joshua Matthews is the third youngest member of the Matthews family (after Auggie and Riley Matthews). Soon after his birth, complications appeared, to the point where Shawn came back from his road trip just to comfort Cory. Joshua is a quite important character in the last episode, as Cory has a very serious talk with him about life, after which he comes to the conclusion that he finally understand what Boy Meets World means. He tells Joshua that he might find a best friend like Shawn, a beautiful girl like Topanga, and that Mr Feeny will probably teach him in every grade he ever has. This way, Cory passed on all of the knowledge he gained in his life to his little brother, ending the series in a beautiful and touching way.
Daniel Jacobs' appearance as Joshua in Brave New World severely alters the continuity of the show, as he should be much younger. This is a continuity error.
Joshua will play a larger role in the sequel series Girl Meets World, appearing as a teenager who has a close relationship with his older brother Cory and niece Riley.