Monica is Ross's younger sister. She later marries Chandler. For most of the show she works as a chef around New York City. Her best friends are Rachel Green and Phoebe Buffay.
Ross is the older brother of Monica. He was college roommates with Chandler and they have been close friends ever since. He was previously married to Carol and has one child with her named Ben. He later ends up with Rachel Green. He has a PhD and is a paleontologist. His best friends are Chandler Bing and Joey Tribbiani.
Chandler went to college with Ross and years later ends up marrying Ross's younger sister Monica! He was roommates with Joey Tribbiani until he moved in with Monica. His best friends are Ross Geller and Joey Tribbiani.
Rachel grew up with Monica and Ross, but lost touch when they went to college. In the show they reunite and Rachel becomes roommates with Monica. She loves fashion. She ends up with Ross. Her best friends are Monica Geller Bing and Phoebe Buffay.
Phoebe Buffay has a twin sister named Ursula. She is always up to something interesting. She is best friends with Rachel Green and Monica Geller Bing.
Joey comes from an Italian family from Queens, New York. He has 7 sisters. Chandler and Joey were roommates after Chandler graduated college. Joey is a wannabe actor throughout the show.