Rainbow was broadcast twice weekly at 12:10pm on Tuesdays and Fridays on ITV. The show was intended to develop language and number skills for pre-school children, and went on to win the Society of Film and Television Arts Award for Best Children's Programme in 1975.

Rainbow was originally conceived as a British equivalent of popular American series Sesame Street. Each episode of Rainbow revolved around a particular activity or situation that would arise in the Rainbow House, where the main characters lived. Usually it would involve some kind of squabble or dispute between the puppet characters of Zippy, George and Bungle, and Geoffrey's attempts to calm them down and keep the peace.

The main story would be interspersed with songs (usually from Rod, Jane and Freddy, although guest singers would occasionally take their place), animations, and stories read from the Rainbow storybook, usually by Geoffrey. Some episodes would focus on a particular theme, such as sounds or opposites, and would consist mainly of short sketches or exchanges between the main characters, rather than a consistent storyline.

Rainbow featured the following characters, each with their own character style:

The presenter: The first presenter was David Cook, who was followed by the best known presenter Geoffrey Hayes.

Bungle: Bungle is a large brown bear who is inquisitive and quite clumsy. The strangest thing about Bungle was that he always wore pyjamas at bedtime, swimming shorts on the beach, and a towel after a shower, yet appeared nude at all other times.

Zippy: Zippy is a loud and domineering character, with a head made from a rugby ball which was attached to a non-descript body. Zippy was a hand operated puppet.

George: George is a shy, pink, slightly camp hippo and was, like Zippy, a hand operated puppet

Rod, Jane and Freddy, a group of musicians who regularly featured on the programme. Originally known as Rod, Matt and Jane when they debuted on the show in 1974, Matt's position being held by Matthew Corbett (of The Sooty Show fame), and Roger Walker from 1977-80 before Freddy Marks took over in 1980.

Zippo: Zippo was Zippy's cousin, identical in appearance to Zippy, who would make the occasional guest appearance.

Dawn: Dawn was the next-door neighbour, played by Dawn Bowden, who was introduced in the show's later years, first appearing in 1986.

Aunty, played by numerous actresses, was the aunt of one of the characters, probably Geoffrey. She came along roughly once a year and always let herself in. She was mainly a tool for teaching stories or morals, as she was a very boring woman.

Generally speaking, George and Zippy represented two 'types' of child, George being the quiet and shy type, while Zippy represented the hyperactive and destructive type (hence his name). George was usually vindicated, and Zippy got his comeuppance. While they were apparently young 'children', Bungle was an older 'child', and differed from them in being a costume, rather than a hand puppet. Geoffrey's relationship to them was unclear, other than being a kind of father figure. Apart from Jane, females rarely appeared on the programme, despite some ambiguity concerning the often effeminate (and permanently pink) George.

After more than 1000 episodes, the series came to an abrupt end when Thames Television lost its ITV franchise in 1992. Since then, it has gained cult status and continues to get frequent mentions on radio and television. On 28 February 2006, BBC News reported that digital children's channel Nick Jr. would be showing repeats of Rainbow (dating from 1982) on Mondays.

The "adult" version

In 1979, the cast and crew of Rainbow made a special exclusive sketch for the Thames TV staff Christmas tape, sometimes referred to as the "Twangers" episode. This show featured plenty of deliberate sexual innuendo (beginning with Zippy peeling a banana, saying "One skin, two skin, three skin, four..." before being interrupted), and never shown at the time (as it was never intended to be screened to the general public).

The show even had Roger saying the word "fuck", when he greeted everyone upon entering the set. This can be heard clearly from his sentence "Hello, everybody, hello! Fuck." Jane also claimed she was blowing with Roger the night before. It also included Geoffrey convincing the viewers to play with their balls, but if they didn't have any balls, they could ask a friend and play with his. Jane also claimed that she was banging with Rod and Roger. Soon, Zippy asked them to stop suggesting whether to play with a blowing tube and maracas, so they could start singing the 'Plucking Song'.

The clip became famous after being aired on Victor Lewis-Smith's Channel 4 programme TV Offal (1997) and was jokingly referred to as "the pilot episode", which it clearly wasn't as Geoffrey Hayes was presenter at the time. The clip has become widely-spread, first in emails as an attachment and later via online video websites such as YouTube. This has led to many erroneous claims that the episode was publicly broadcast as a regular episode.