AT&T is a large US company that sells telephone and digital services and equipment — phone lines, mobile plans, internet, that kind of thing. The letters come from its old name, American Telephone and Telegraph Company. People still say “A-T-and-T,” not “att.” In the US it is a name everyone knows, like a huge, slightly old utility that also lives on your mobile screen. Though actually, the company behind the letters has been broken up, rebuilt, and restyled more than once; in 2005 it even changed how the brand looks, while keeping the same famous letters. For a student in Taiwan it turns up in US news, in old Hollywood, or on a phone bill from a year abroad. It is a company name, not a type of technology. You cannot buy “an AT&T” the way you buy “a Wi-Fi.”