Relativistic mass is discussed in both a pedagogical and historical context. It is pointed out that its introduction into the theory of special relativity was much in the way of a historical accident. Gaining widespread use initially in instruction, the use of relativistic mass is showing signs of progressive disfavor. An analysis and criticism of the various ways relativistic mass is used in relativity is detailed and special attention is given to the frequent misuse of relativistic mass as an inertia.

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