When your friend is eyeing members of the opposite sex at the local watering hole, “datum” (pronounced “day-tum”), is not appropriate advice. Datum is the singular form of “data”. It is a Latin noun meaning “something given.” Therefore, a bucket of datum is data (or a bunch of given somethings): but, what exactly is data?
Wikipedia describes data as, “…qualitative or quantitative attributes of a variable or set of variables.” Huh? Not to worry, they make it perfectly clear later on: “Data are often viewed as the lowest level of abstraction from which information and then knowledge are derived.” Right! This kind of stuff will have you repeating that famous expression from Homer Simpson - “doh!”
A datum is commonly a measurement, a fact, a number, an image and the like. Without being put into some context, a datum has no meaning. Take, for example, “9”. Nine is a datum, but nine what? How about nine beers? “Nine beers” is information rather than a datum. “After drinking nine beers, my friend pointed at all the cuties in the bar and started yelling, “date’m.” That’s knowledge. It’s useless, but knowledge nonetheless. Can you see how data builds into information that builds into knowledge?
Furthermore, “data” is a mass noun. It is the plural form of a word that is treated as if it’s singular. How many times have you heard, “The data are a mess.” Never. It’s always, “The data IS a mess.” That’s a plural noun with a singular verb. This is not only common usage but grammar scholars generally shake their heads and accept it as inevitable.
In the printing world, we talk about variable data printing. In reality, VDP might really be called variable information printing or “VIP” since it is often information, rather than data, that is most commonly used to personalize printed materials. "John Smith, 823 Green Street, Somewhere, TX" is information, not data. Or, is it?
When we take a bunch of information, like mail addresses, and break it down into records and fields (as in a spreadsheet- |John|Smith|823 Green Street|Somewhere|TX|), each cell becomes a datum (|Smith|) and all the cells with our mailing address information would correctly be called data. In printing terms, the distinction between data and information is pretty fuzzy, and the two terms can be (and are) used interchangeably.