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.”
Data, which originated as the plural of the Latin datum, may be used as a plural count noun or as a singular mass noun (The data are/is conclusive). More often than not, in both speech and writing, data is treated as a mass noun that takes singular verbs and pronouns (much like the word information). These days, data is used as a plural noun mainly in written material, such as academic and scientific papers. While writing, consider whether you want to convey the sense of a plural noun (the data indicate that . . .) or a mass noun (the data has been downloaded).