Originally a British paperback publisher, started in 1935 by Allen Lane, then a director of The Bodley Head. The first Penguin paperbacks appeared in the summer of 1935 and were colour-coded (orange for fiction, blue for biography, green for crime) and cost just sixpence.
Penguin became a separate company in 1936 and set up premises in the Crypt of the Holy Trinity Church on Marylebone Road, London. In 1937 they moved to new offices and a warehouse in Harmondsworth, Middlesex. 1937 also saw the start of the "Penguin Shakespeare" series and the "Pelican" imprint. "Penguin US" was started in 1939. The Puffin imprint was born in 1940, and Penguin Classics in 1946. Penguin became a public company in 1961. In 1967 "Allen Lane The Penguin Press" was created, which allowed Penguin to publish in both hardback and paperback.
In 1970, the international media group "Pearson" bought Penguin. In 1983, they also acquired Frederick Warne, best known for its Beatrix Potter titles: in 1984, they set up the Viking imprint: in 1985 they bought the Michael Joseph and Hamish Hamilton book-publishing divisions. In 1993, Penguin Audiobooks was launched. In 2000, Pearson bought Dorling Kindersley and added it to the Penguin Group in the UK. "Penguin Ireland" started in 2003.
Source: Penguin website, 20th September 2008