A week is a time unit equal to seven days. The English word week continues an Old English wice, ultimately from a Common Germanic *wikōn-, from a root *wik- "turn, move, change". The Germanic word probably had a wider meaning prior to the adoption of the Roman calendar, perhaps "succession series", as suggested by Gothic wikō translating taxis "order" in Luke 1:8. The term "week" is sometimes expanded to refer to other time units comprising a few days. Such "weeks" of between four and ten days have been used historically in various places. Intervals longer than 10 days are not usually termed "weeks" as they are closer in length to the fortnight or the month than to the seven-day week.

Evidence of continuous use of a seven-day week appears with the Jews during the Babylonian Captivity of the 6th century BC. Both Judaism (based on the Creation narrative in the Bible) and ancient Babylonian religions used a seven-day week. Other cultures adopted the seven-day week at different times. Between the 1st and 3rd centuries the Roman Empire gradually replaced the eight-day Roman nundinal cycle with the seven-day week. Hindus may have adopted a seven-day week earlier than 11th century BC.^{[citation needed]} See Rig Veda. There is evidence of some Chinese groups using a seven-day week as early as 4th century.

Meryl Davis (born January 1, 1987) is an American ice dancer. With partner Charlie White, she is the 2011 World champion, 2010 Olympic silver medalist, the 2010 World silver medalist, three-time Grand Prix Final champion (2009–2011), two-time Four Continents champion (2009, 2011) and four-time U.S. national champion (2009–2012).

Davis and White teamed up in 1997 and they are currently the longest lasting dance team in the United States. They are the first American ice dancers to win the World title. At the 2006 NHK Trophy, they became the first ice dancing team to earn level fours on all their elements.

At the 2010 U.S. Championships, they were nominated to represent the United States at the 2010 Winter Olympics. They won the silver medal in the ice dancing event.

Davis and White are the current world record holders for the short dance.

Meryl Davis was raised in West Bloomfield, Michigan. She lives and attends school in Ann Arbor, Michigan and trains in Canton, Michigan.

In June 2005, Davis graduated from Wylie E. Groves High School. She was a member of the National Honor Society and, upon graduation, received the Phi Beta Kappa Society award. She attends the University of Michigan, where she is majoring in cultural anthropology, and also studying Italian. She is an active member of the sorority Delta Delta Delta. She can play the flute.

Maksim (Maks) Aleksandrovich Chmerkovskiy (Ukrainian: Максим Олекса́ндрович Чмерковський, Maksym Oleksándrovych Čmerkovsʹkyj, pronounced [mɑkˈsɪm olɛkˈsɑndroβ̞ɪtʃ ˈtʃmɛrkou̯sʲkɪj]; Russian: Максим Александрович Чмерковский; born January 17, 1980) is a Ukrainian-American Latin Ballroom dance champion, choreographer, and instructor. He is best known as one of the professional dancers on the American television series Dancing with the Stars, on which he first appeared in season two. In his ten appearances on the show, Chmerkovskiy has made it to the final round four times, with two runner-up and two third place finishes.

Born on January 17, 1980, in Odessa (Ukraine) to Aleksandr and Larisa Chmerkovskiy, he began dancing at the age of four. His brother, Valentin Chmerkovskiy, is also a champion dancer. His father is Jewish and his mother is Christian. Chmerkovskiy's Ukrainian heritage was referenced on an episode of Dancing with the Stars.

The challenges of immigration for Chmerkovskiy and his family included financial and language barriers. A skiing accident as a child broke Chmerkovskiy's right leg. Doctors informed him that there would be difficulties with his leg and that dancing might not be possible. He made a successful recovery and went on to become a professional Latin Ballroom dancer.

Amy Purdy was born in Las Vegas. She is a double amputee, competitive snowboarder and spokesperson for the Challenged Athletes Foundation.

At the age of 19, she contracted Neisseria meningitis, a form of bacterial meningitis. Due to the disease, which affected her circulatory system, both of her legs had to be amputated below the knee. Her spleen and a kidney had to be removed. Two years later, she received a kidney transplant from her father. Her friends now refer to her by the nickname Lucky.

Purdy began snowboarding seven months after she received her leg prosthetics. About a year after her legs were amputated, she came in third place in a snowboarding competition in Mammoth. Subsequently, she received a grant from the Challenged Athletes Foundation (CAF), a non-profit organization. Through this grant, she was able to compete in several snowboarding competitions in the U.S.

In 2003, Purdy was recruited by the CAF as spokesperson. She moved to San Diego to be closer to the CAF headquarters. In San Diego, she continued her pre-amputee profession as a massage therapist. She also got involved in the modeling and acting industry. In February 2003, she played a model in a Madonna music video. Later in 2003, Purdy started working for Freedom Innovations, a prosthetic feet manufacturer, as Amputee Advocate. She has gone on to co-found her own non-profit organization, Adaptive Action Sports, for individuals with physical disabilities who want to get involved in action sports (snowboarding, skateboarding, surfing) or art and music.

Derek Hough ( /ˈhʌf/; born May 17, 1985) is an American dancer, choreographer, musician and actor. A world champion in Latin American Dance, Hough has appeared since September 2007 (Seasons 5 - 11 and Season 13) on the hit U.S. television series Dancing with the Stars, where he is currently a three-time champion (with Brooke Burke, Nicole Scherzinger, and Jennifer Grey), one-time finalist (with Ricki Lake), three-time semi-finalist (with Jennie Garth, Joanna Krupa, and Maria Menounos), and a quarter-finalist (with Lil' Kim). Hough has earned three Creative Arts Primetime Emmy nominations for Outstanding Choreography (2009 and 2010 ) for his work on the show.

Prior to joining Dancing with the Stars, Hough starred as Ren in the 2006 original cast production of Footloose: The Musical at the Novelo Theatre in London's West End, as well as on the 2006 U.K. national tour. Hough's West End performance earned him a nomination as The Stuart Phillips London Newcomer of the Year in the Whatsonstage.com Theatregoers' Choice Awards. Hough made his Broadway debut on January 8, 2010, starring with Kym Johnson and Mary Murphy in Burn the Floor for the final four performances of the show's Broadway run. A founding member of the Ballas Hough Band (formerly Almost Amy), Hough shares lead vocals, plays guitar and has several songwriting credits on the band's self-titled debut CD, released by Hollywood Records in March 2009.