BYOD stands for bring your own device. It is a school or office practice: workers or students use their own phone, tablet, or laptop, instead of a computer the school or company gives them. Sometimes this is allowed; sometimes people are asked to do it. IT staff and managers say the letters; it feels like workplace and school English, not home English. It can name a policy (“We are a BYOD school”) or the setup itself. The idea saves money and lets people use tools they already know, but it also brings worries about safety, passwords, and whose job it is to fix the machine. Though actually nobody is asking you to bring a device to a party — that older idea is BYOB, bring your own beer.