X射线或X射线是电磁波谱的一部分，波长比可见光波长（频率高）。 X射线波长范围为0.01至10纳米，或频率范围为3×1016Hz至3×1019Hz。这使得X射线波长介于紫外光和伽马射线之间。 X射线和伽马射线之间的区别可以基于波长或基于辐射源。有时x射线被认为是电子发射的辐射，而伽马射线是由原子核发射的。德国科学家WilhelmRöntgen是第一个研究X射线的人（1895年），尽管他不是第一个观察X射线的人。观察到的X射线是从大约1875年发明的克鲁克斯管发出的。伦琴称光“X射线”表明它是以前未知的类型。有时，辐射被称为Röntgen或伦琴辐射，仅次于科学家。接受的拼写包括X射线，X射线，X射线和X射线（和辐射）。术语x射线还用于指代使用x射线形成的射线照相图像以及用于产生图像的方法。
英国伦敦国王学院Assignment代写：X射线定义和属性
X-rays or x-radiation are part of the electromagnetic spectrum with shorter wavelengths (higher frequency) than visible light. X-radiation wavelength ranges from 0.01 to 10 nanometers, or frequencies from 3×1016 Hz to 3×1019 Hz. This puts the x-ray wavelength between ultraviolet light and gamma rays. The distinction between x-ray and gamma rays may be based on wavelength or on radiation source. Sometimes x-radiation is considered to be radiation emitted by electrons, while gamma radiation is emitted by the atomic nucleus. German scientist Wilhelm Röntgen was the first to study x-rays (1895), although he was not the first person to observe them. X-rays had been observed emanating from Crookes tubes, which were invented circa 1875. Röntgen called the light “X-radiation” to indicate it was a previously unknown type. Sometimes the radiation is called Röntgen or Roentgen radiation, after the scientist. Accepted spellings include x rays, x-rays, xrays, and X rays (and radiation). The term x-ray is also used to refer to a radiographic image formed using x-radiation and to the method used to produce the image.