Red letter edition

Red letter edition bibles are those in which the "Dominical" words—those spoken by Jesus Christ, commonly only those spoken during his corporeal life on Earth—are printed rubricated, in red ink. This is a modern practice derived from the art and Roman Catholic practice in mediaeval "scriptoria" of rubricating headings, leading letters of sectional text, and words of text in manuscripts for emphasis, similar to italicization.
History.
The inspiration for rubricating the Dominical words comes from Luke, 22:20: "This cup is the new testament in my blood, which I shed for you." On 19 June 1899, Louis Klopsch, then editor of "The Christian Herald" magazine, conceived the idea while working on an editorial. Klopsch asked his mentor Rev. Thomas De Witt Talmage what he thought of a testament with the Dominical words rubricated and Dr. Talmage replied, "It could do no harm and it most certainly could do much good."
Klopsch published the first modern red letter edition New Testament later in 1899. The first modern, fully rubricated bible was published in 1901. The rubricated bible instantly became popular, and is sometimes favored by Protestant Christians in the United States. Especially in King James Version editions, this format is useful because quotation marks are absent.
Qualifications.
Because the original texts of the Sacred Scriptures do not have quotation marks, which words exactly are Dominical has been interpreted, as opposed to explanatory text that follows them. For example, a footnote in the New International Version for John, 3:21 explains that "Some interpreters end the quotation after verse 15." In addition, some publishers have chosen to rubricate the Dominical words after His Ascension to Heaven, for example, His words spoken to Saul on the road to Damascus in Acts of the Apostles, 9, and the Dominical words spoken to St. John in Revelation, 1-3. Thus, rubrications may not exactly correspond to Dominical words and may vary by edition.
A feature of the first Klopsch edition is that the Dominical words were also italicized. This rather defeated the specific use of italics in the King James Version to mark words supplied by the translators that are not present in the original texts. From the title page:
Red Letter Edition<br>WITH THE WORDS OF OUR LORD AND SAVIOUR<br>SET FORTH IN DIGNIFIED RED ITALICS