Moss is a coastal town and a municipality in Østfold county, Norway. The administrative centre of the municipality is the town of Moss. The city of Moss was established as a municipality on 1 January 1838 and City in 1720. The rural municipality of Jeløy was merged with the city on 1 July 1943. The former municipality of Rygge was merged into it on January 1, 2020.

The Convention of Moss (Mossekonvensjonen) was a ceasefire agreement signed on 14 August 1814 between the King of Sweden and the Norwegian government. It followed the Swedish-Norwegian War due to Norway's claim to sovereignty. It also became the de facto peace agreement and formed the basis for the personal union between Sweden and Norway that was established when the Norwegian Stortinget (Parliament) elected Charles XIII of Sweden as king of Norway on 4 November 1814. The Union lasted until Norway declared its dissolution in 1905.