Youth is the time of life between childhood and adulthood (maturity). Definitions of the specific age range that constitutes youth vary. An individual's actual maturity may not correspond to their chronological age, as immature individuals could exist at all ages.

Around the world, the terms "youth", "adolescent", "teenager", "kid", and "young person" are interchanged, often meaning the same thing, occasionally differentiated. Youth generally refers to a time of life that is neither childhood nor adulthood, but rather somewhere in-between. Youth also identifies a particular mindset of attitude, as in "He is very youthful". The term youth is also related to being young.

Youth is an alternative word to the scientifically-oriented adolescent and the common terms of teen and teenager. Another common title for youth is young person or young people.

August 12th was declared International Youth Day by The United Nations.

The age in which a person is considered a "youth", and thus eligible for special treatment under the law and throughout society varies around the world.

Donald Ervin Knuth ( /kəˈnuːθ/kə-NOOTH; born January 10, 1938) is a computer scientist and Professor Emeritus at Stanford University.

He is the author of the seminal multi-volume work The Art of Computer Programming. Knuth has been called the "father" of the analysis of algorithms. He contributed to the development of the rigorous analysis of the computational complexity of algorithms and systematized formal mathematical techniques for it. In the process he also popularized the asymptotic notation.

In addition to fundamental contributions in several branches of theoretical computer science, Knuth is the creator of the TeX computer typesetting system, the related METAFONT font definition language and rendering system, and the Computer Modern family of typefaces.

As a writer and scholar, Knuth created the WEB/CWEB computer programming systems designed to encourage and facilitate literate programming, and designed the MIX/MMIX instruction set architectures.

Knuth was born in Milwaukee, Wisconsin, where his father owned a small printing business and taught bookkeeping at Milwaukee Lutheran High School, where he enrolled, earning achievement awards. He applied his intelligence in unconventional ways, winning a contest when he was in eighth grade by finding over 4,500 words that could be formed from the letters in "Ziegler's Giant Bar." The judges had only about 2,500 words on their master list. This won him a television set for his school and a candy bar for everyone in his class.

Andrei Arsenyevich Tarkovsky (Russian: Андре́й Арсе́ньевич Тарко́вский; April 4, 1932 – December 29, 1986) was a Soviet and Russian filmmaker, writer, film editor, film theorist, theatre and opera director, widely regarded as one of the finest filmmakers of the 20th century.

Tarkovsky's films include Andrei Rublev, Solaris, The Mirror, and Stalker. He directed the first five of his seven feature films in the Soviet Union; his last two films were produced in Italy and Sweden, respectively. They are characterized by spirituality and metaphysical themes, long takes, lack of conventional dramatic structure and plot, and distinctively authored use of cinematography.

Film director Ingmar Bergman said of Tarkovsky:

Tarkovsky was born in the village of Zavrazhye in Ivanovo Oblast, the son of poet and translator Arseny Alexandrovich Tarkovsky, native of Kirovohrad, Ukraine, and Maria Ivanova Vishnyakova, a graduate of the Maxim Gorky Literature Institute.

Leonard Bernstein ( /ˈbɜrnstaɪn/ US dict: bûrn′·stīn; August 25, 1918 – October 14, 1990) was an American composer, conductor, author, music lecturer and pianist. He was among the first conductors born and educated in the United States of America to receive worldwide acclaim. According to The New York Times, he was "one of the most prodigiously talented and successful musicians in American history."

His fame derived from his long tenure as the music director of the New York Philharmonic, from his conducting of concerts with most of the world's leading orchestras, and from his music for West Side Story, as well as Candide, Wonderful Town, On the Town and his own Mass.

Bernstein was also the first conductor to give numerous television lectures on classical music, starting in 1954 and continuing until his death. In addition, he was a skilled pianist, often conducting piano concertos from the keyboard.

As a composer he wrote in many styles encompassing symphonic and orchestral music, ballet, film and theatre music, choral works, opera, chamber music and pieces for the piano. Many of his works are regularly performed around the world, although none has matched the tremendous popular and commercial success of West Side Story.