The name of one of the world's most famous auction houses — a company that sells valuable things, especially art, antiques, rare books, jewellery and wine, by auction, where buyers call out higher and higher prices until nobody will go higher. It was founded in London in the 1740s and now has its main offices in London and New York, with sale rooms in Hong Kong and other cities. Two things make the name useful to a learner. First, it almost always appears in a pair with Christie's, its old rival; 'Sotheby's and Christie's' is how English talks about the top end of the art market, the way 'Harvard and Yale' works for universities. Second, the name has become a kind of shorthand for 'extremely expensive and important'. If someone says 'that vase belongs at Sotheby's', they are not booking an auction — they mean the thing is grand, or they are teasing you for treating a cheap object like treasure. Note the apostrophe-s. It is there because the company is named after Mr Sotheby, so the full sense is 'Sotheby's place of business' — the same pattern as 'the dentist's' or 'McDonald's'. Because of that, the -'s is part of the name and never gets dropped, and the word takes a singular verb: 'Sotheby's is selling it', not 'are'.