Lincoln–Douglas debate (commonly abbreviated as LD Debate, or simply LD) is a type of one-on-one competitive debate practiced mainly in the United States at the high school level. It is sometimes also called values debate because the format traditionally places a heavy emphasis on logic, ethical values, and philosophy. The Lincoln–Douglas debate format is named for the 1858 Lincoln–Douglas debates between Abraham Lincoln and Stephen A. Douglas, because their debates focused on slavery and the morals, values, and logic behind it. LD debates are used by the National Speech and Debate Association, or NSDA (formerly known as the National Forensics League, or NFL) competitions, and also widely used in related debate leagues such as the National Christian Forensics and Communication Association,