The Editor’s Manual
Free learning resource on English grammar, punctuation, usage, and style.
Data can be a plural noun (“the data are”) or a singular mass noun (“the data is”). As a mass noun, it is used much like the word “information.”
Count nouns have singular and plural forms (e.g., star/stars). Mass nouns are thought of in terms of quantity rather than number of units, and have no distinct singular and plural forms (e.g., milk, excitement, oxygen).
Form the plural of an acronym or other abbreviation simply by adding “s” to the end (URLs, CEOs). No apostrophe is necessary.