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`November 8, 1995 marks the 100th anniversary of the discovery of X-rays. While experimenting with a vacuum tube (Crookes tube) to produce cathode rays, Wilhelm Conrad Roentgen, a German physicist, discovered a mysterious of electromangetic radiation with wavelengths of 0.01∼100 angstroms (1 angstrom [Å] equal to 1×10-8mm) between the ranges extrems of ultraviolet and gamma-ray (r-ray)ranges on November 8, 1895. He dubbed the newly discovered from of radiation the X-rays, to indicate that its nature was unknown. X-rays are invisible and are characterized by their particular types of behavior in reflection, refraction, and diffraction. They have high fluorescent, polartzing and penetrating power. The dicovery of X-rays ushered in a new era of grealy increased precision in the diagnostic examination of the human body. Until then, medical diagnoses relied on visul inspection, percussion and auscultation. Beyond their well-known applications in the diagnosis and treatment of diseases, and sterilization of food and pharmceuticals, X-rays are also a major tool in archeological reserch and in industrial applications. X-ray inspection, in particular, is used in more than 70 percent of diagnosing activities throughtout the world. Roentgen received the first Nobel Prize pysics in 1901 for his discovery of X-rays. Marking the centennial of the discaovery of X-rays and the 150th anniversary of Roentgen`s birth, the Ministry of Information and Communication is issuing a commemorative postage stamp to celebrate the significant contribution of X-rays as an essential element to further scientific development in the next century.`