English is a human language that originated in England. The current form of the English language is in the era known as Late Modern English, having already been through three earlier incarnations. Its roots lie in the northern Germanic languages of Celtic Europe which it is speculated the Asgard originally helped contribute towards.
After the Anglo-Saxons invaded Britain, the original Celtic language was merged with the Germanic languages. Influences also from the Vikings were seeded and the invasion of Britain by the Normans contributed vastly as well in terms of French.
- The producers make almost all newly encountered people on alien planets speak English for the sake of convenient storytelling, though their writing is invariably alien. The characters on the shows seem to be generally unaware of the "miracle English" phenomenon, although it was subtly parodied in the episode "Wormhole X-Treme!" of Stargate SG-1. Stargate Universe has generally attempted to avoid the phenomenon except in cases where it's in keeping with canon (namely the Lucian Alliance), instead creating aliens with their own language or alternate means of communication.
- In a few episodes of Stargate SG-1, characters that appear to be speaking English are most likely speaking their own language, which is simply being translated for viewer convenience. Examples include the Goa'uld meeting in "Summit" and the Ancients in the beginning of Stargate: The Ark of Truth.