The series focuses on their attempt to fit in while trying to fix their time machine and return to the year 2121.

Phil of the Future is an American comedy children's television series that was produced by 2121 Productions (a part of Brookwell McNamara Entertainment). Phil of the Future's working title was The Out of Timers. It debuted on June 18, 2004 on the Disney Channel and ended on August 19, 2006. It centers around the Diffys, a family from 2121 who get stuck in the 21st century during their trip through time. The series focuses on their attempt to fit in while trying to fix their time machine and return to the year 2121.

As of January 2007, the second season of "Phil" has been nominated for a Writer's Guild of America Award (Children's Series) for "Broadcast Blues," (written by David Steven Cohen) and a Directors' Guild of America Award (Children's Series) for "Not-So-Great-Great Grandpa," directed by Fred Savage.

Phillip "Phil" Diffy (born 2104), played by Raviv Ullman: Phil Diffy is the main character in the series. He is a 9th (Season 1) / 10th (Season 2) grader at H.G. Wells Junior/Senior High. He seems to be the most "in tune" with how things work in this century. Phil frequently has to make up excuses to hide the fact that he is from the future. He is best friends with Keely Teslow, for whom he develops romantic feelings in season 2 and at the end of the season they become a couple.

Pim Diffy (born 2107), played by Amelia Ellen Bruckner: Pim Diffy is Phil's younger sister. She is a 7th (Season 1) / 8th (Season 2) grader at H.G. Wells Junior/Senior High. Pim is a mischievous girl who is constantly up to no good. Pim is especially known for liking to pull pranks on people, mainly on Phil, Debbie Berwick and Vice Principal Hackett. Pim tries to make Phil miserable whenever she can. She hangs out with a young boy "Li'l Danny" Dawkins. She also tries to avoid Debbie Berwick and Candida. Repeatedly in the show, she looks for ways to dominate the world, and universe. Even though Pim often causes trouble for Phil, and has a tough attitude, she also cares about her brother but keeps it hidden most of the time. It's unclear whether Pim is her actual name or if it's short for something.

Lloyd Diffy (born 20??), played by Craig Ward Anton: Lloyd Diffy is Phil and Pim's goofy dad, who is working on repairing the time machine. He was an engineer in 2121, and loves "older music". He is paranoid about the government (and Vice Principal Hackett) figuring out he and his family are from the future. During the Diffys' stay, Lloyd and Curtis got jobs at the Mantis hardware store.

Barbara (née Speckle) Diffy (born 20??), played by Elisabeth Caroline Simms: Barbara Diffy is Phil and Pim's mom. She's very interested how things work in this century. Unlike other mothers though, Barbara seems to let her kids figure things out on their own. She loves to cook the old fashion way, however her food usually ends up with something being wrong, because in 2121 they spray food out of a can.

Keely Teslow (born 1989), played by Alyson Renae Michalka: Keely Teslow is Phil's best friend. She is the only person who knows Phil and his family are from the future. Keely Teslow is an energetic and bubbly girl who aspires to be a reporter. She starts to harbor romantic feelings for Phil during season 2 and at the end the end of the season they become a couple. She sometimes uses Phil's gadgets as a shortcut for schoolwork. She is notable on the show for her numerous hairstyles and colorful clothes. In the later episodes of the show, she hosts her own, daily news program on the school's closed circuit broadcasting system. In the episode The Giggle, she gets to look ahead at her own future and learns that she does become a successful news reporter.

Curtis the Caveman played by J.P. Manoux: Curtis is a Caveman who stowed away in the Diffy's time machine when they went back to visit the Stone Age. The Diffys struggle to make Curtis seem like a normal person, and often pretend he is Phil's uncle. Throughout the episodes, he learns more English.

Vice Principal Neal Hackett played by J.P. Manoux: Vice Principal Hackett is the Vice Principal at Phil, Keely and Pim's school, H.G. Wells Junior/Senior High School. He is often found snooping around the Diffys' lives trying to figure out where they are really from, though he believes that they are aliens.