Novum Testamentum Graece is the Latin name of a compendium source document of the New Testament in its original Greek-language, and the modern day standard for translations and analysis. The first printed edition was the Complutensian Polyglot Bible by Cardinal Francisco Jiménez de Cisneros, printed in 1514, but not published until 1520. The first published edition of the Greek New Testament was produced by Desiderius Erasmus in 1516.
Today the designation Novum Testamentum Graece normally refers to the Nestle-Aland editions, named after the scholars who led the critical editing work. The text, edited by the Institut für neutestamentliche Textforschung (Institute for New Testament Textual Research) is currently in its 28th edition, abbreviated NA28. The Nestle-Aland text is the primary source for most contemporary New Testament translations, although most are translations of the edition that was available at the time of translation. The Nestle-Aland text is also the standard for academic work in New Testament studies.
The title Novum Testamentum Graece can also be applied to the United Bible Societies (UBS) edition which contains the same base text (the latest UBS 5th ed, "UBS5," contains the text from the NA28). The primary difference between the NA and UBS editions is that the latter is aimed at translators and so focuses on variants that are important for the meaning whereas the NA includes more variants for textual criticism.
The Greek text as presented is what biblical scholars refer to as the "critical text". The critical text is an eclectic text compiled by a committee that examines a large number of manuscripts in order to determine which reading is most likely to be closest to the original. They use a number of factors to help determine probable readings, such as the date of the witness (earlier is usually better), the geographical distribution of a reading, and the likelihood of accidental or intentional corruptions. In the book, a large number of textual variants, or differences between manuscripts, are noted in the critical apparatus—the extensive footnotes that distinguish the Novum Testamentum Graece from other Greek New Testaments.