This paper presents a recommended terminology for reporting measurements of "black carbon" (BC), "elemental carbon" (EC), "light absorption", "refractory carbon", and other properties related to BC. The authors aim to clarify the terms used for BC in atmospheric research and establish unambiguous links between terms, targeted material properties, and associated measurement techniques. Black carbon is defined as a light-absorbing, carbonaceous material with a graphite-like microstructure, while elemental carbon refers to carbon not bonded to other elements. These definitions are based on formal descriptions and are not always practical for real-world applications due to the complex nature of atmospheric aerosols. The paper discusses various analytical methods used to measure BC, including evolved carbon methods, light absorption techniques, laser-induced incandescence, Raman spectroscopy, and aerosol mass spectrometry. Each method has its own strengths and limitations, and the results can vary depending on the measurement technique used. The authors also highlight the importance of using consistent terminology in atmospheric research to ensure clarity and comparability of data. They recommend using specific terms such as "refractory black carbon" (rBC) for measurements derived from incandescence methods and "equivalent black carbon" (EBC) for data from optical absorption methods. The paper emphasizes the need for standardized reporting of BC-related measurements, including the use of appropriate calibration and conversion methods. It also notes the challenges in defining BC due to its complex composition and the various measurement techniques available. The authors conclude that a consistent terminology is essential for accurate and reliable reporting of BC-related data in atmospheric research.This paper presents a recommended terminology for reporting measurements of "black carbon" (BC), "elemental carbon" (EC), "light absorption", "refractory carbon", and other properties related to BC. The authors aim to clarify the terms used for BC in atmospheric research and establish unambiguous links between terms, targeted material properties, and associated measurement techniques. Black carbon is defined as a light-absorbing, carbonaceous material with a graphite-like microstructure, while elemental carbon refers to carbon not bonded to other elements. These definitions are based on formal descriptions and are not always practical for real-world applications due to the complex nature of atmospheric aerosols. The paper discusses various analytical methods used to measure BC, including evolved carbon methods, light absorption techniques, laser-induced incandescence, Raman spectroscopy, and aerosol mass spectrometry. Each method has its own strengths and limitations, and the results can vary depending on the measurement technique used. The authors also highlight the importance of using consistent terminology in atmospheric research to ensure clarity and comparability of data. They recommend using specific terms such as "refractory black carbon" (rBC) for measurements derived from incandescence methods and "equivalent black carbon" (EBC) for data from optical absorption methods. The paper emphasizes the need for standardized reporting of BC-related measurements, including the use of appropriate calibration and conversion methods. It also notes the challenges in defining BC due to its complex composition and the various measurement techniques available. The authors conclude that a consistent terminology is essential for accurate and reliable reporting of BC-related data in atmospheric research.