Roman Imperial Coinage, abbreviated RIC, is a British catalogue of Roman Imperial currency, from the time of the Battle of Actium (31 BC) to Late Antiquity in 491 AD. It is the result of many decades of work, from 1923 to 1994, and a successor to the previous 8-volume catalogue compiled by the numismatist Henry Cohen in the 19th Century.
The RIC comprises 13 volumes:

volume 1 : AugustusVitellius (31 BC69 AD), by C. H. V. Sutherland, London, 1923 (revised 1984)
volume 2 : VespasianHadrian (69138), by Harold Mattingly, Edward Allen Sydenham, London, 1926
volume 3 : Antoninus PiusCommodus (138192), by H. Mattingly, E.A. Sydenham, London, 1930
volume 4a : PertinaxGeta VII and Caracalla (193217), by H. Mattingly, E. A. Sydenham, London, 1936
volume 4b : MacrinusPupienus (217238), by H. Mattingly, E.A. Sydenham, C. H. V. Sutherland London, 1930
volume 4c : Gordian IIIUranius Antoninus (238253), by H. Mattingly, E. A. Sydenham, C.H.V. Sutherland, London, 1949
volume 5a : ValerianFlorian (253276), by Percy H. Webb, London, 1927
volume 5b : Marcus Aurelius ProbusMaximian (276310), by Percy H. Webb, London, 1933
volume 6 : The Diocletian ReformMaximinus II (294313), by C. H. V. Sutherland, London, 1967
volume 7 : Constantine ILicinius (313337), by P. M. Bruun, 1966
volume 8 : The Family of Constantine I (337364), by J. P. C. Kent, London, 1981
volume 9 : Valentinian ITheodosius I (364395)
volume 10 : The Divided Empire, 395491, by J. P. C. Kent, London, 1994
Western Roman Empire : Flavius HonoriusRomulus Augustus (395-476)
Eastern Roman Empire : Flavius ArcadiusZeno (395-491)

Each emperor is given a detailed history of the coinage of his reign, with a classification of the type of money, and within each type a registration, from its inscription.

For each coin listed, there is a description of both the obverse and reverse sides of the coin (heads and tails), and a notation depending on the rarity of known examples:

C: common
R1: rare, only twenty or so known
R2: between five and fifteen known
R3: four or five known
R4: two or three known
R5: only one known, unique

In the endpapers of each volume is a table of the coins that have reproductions.