The Observer is a British newspaper published on Sundays. It is a sister paper to The Guardian and The Guardian Weekly, having been acquired by their parent company, Guardian Media Group Limited, in 1993. First published in 1791, it is the world's oldest Sunday newspaper.The Observer is a British newspaper published on Sundays. It is a sister paper to The Guardian and The Guardian Weekly, having been acquired by their parent company, Guardian Media Group Limited, in 1993. First published in 1791, it is the world's oldest Sunday newspaper....more