Data-Datum | Commonly Confused Words

Data

/ˈdeɪtə/

Facts or information used for analysis or to make decisions

That data is for them.That data is about the whole city.His research suffered due to corrupt data files.

This word has no antonyms

A single piece of information or fact, often used as the singular form of data

The datum indicated a rise in visitor numbers.Researchers analyzed each datum individually for accuracy.A single erroneous datum skewed our results.

Data is the plural form, think of it as a collection of instances or measurements.
Datum is singular, think of it as a single instance or measurement.
When referring to multiple pieces of information, always use data.
In scientific contexts, be precise: use datum for single measurements.
Most modern contexts use data as a singular mass noun, like information.