Transformers: Generation 1 (also known as Generation One or G1) is a children's toy line that ran from 1984 to 1990, produced by Hasbro and Takara. It was a line of toy robots that could change into an alternate form (vehicles such as cars and planes, miniature guns or cassettes, animals, and even dinosaurs) by moving parts into other places, and it was the first line of toys produced for the successful Transformers toy and entertainment franchise. The line was originally called The Transformers, with "Generation 1" originating as a term coined by fans of the toys when the Transformers: Generation 2 toy line was released in 1992. Hasbro eventually adopted the term "Generation 1" to refer to any toy produced in that era.
Source: Wikipedia, "[en.wikipedia.org/wiki/The_Transformers_%28TV_series%29 The Transformers (TV series)]", available under the CC-BY-SA License.