Metadata is information that describes other information. The photo is the data; the metadata might say when it was taken, which camera, the file size, and the file name. In a large computer database, metadata tells you who wrote a record, what it is for, and in what form it is stored, so you do not have to open every file. Librarians, programmers, and anyone who organizes digital things use this word. Though actually, news stories about privacy now use it for the hidden trail a phone leaves — time, place, who you contacted — not the message itself. That is the same idea: data about data. It is a technical word, but it has moved into ordinary talk about computers and privacy. Meta- here does not mean “big.” A tiny note can still be metadata.