Electromagnetic wavelengths run from kilometres at the long end to smaller than an atom at the short end, some fifteen orders of magnitude. Laid out in proportion there would be no band to look at, so the figure lays out the powers of ten instead.
From the long end the names run radio, microwave, infrared, visible, ultraviolet, X-ray, gamma ray. The borders are not sharp; they are rough lines drawn by how the waves are made and what they are used for.
The visible range is one thin stripe of the whole band. The figure pulls that stripe out below and gives it colour. It is through that width that people see the world.
There are seven names but not seven kinds of wave. Every one of them is the same wave of fields creating each other as they travel, and the only difference is the wavelength.
In empty space they all move at the same speed. A television signal, visible light and the X-rays in a radiograph all travel at 299.8 million metres per second.
Move the pointer in the figure and the name changes over and over as the wavelength shrinks. The wave itself looks the same the whole way.
What a wave passes and what it strikes is decided by its wavelength against the size of the object. Much longer and it bends around and carries on, comparable and it scatters, much shorter and it is stopped.
Radio reaches into the shadow of a building because its wavelength, tens of centimetres to metres, bends around the details of the building. Visible light does not pass a wall because its wavelength is far shorter.
X-rays crossing flesh but stopping at bone is the same story. Their wavelength is close to the spacing between atoms, so the arrangement of atoms catches them. That is also why firing X-rays at a crystal reveals how its atoms are arranged.
Looked at closely, electromagnetic waves are exchanged as particles called photons. One photon carries , an energy proportional to the frequency.
The shorter the wavelength the higher the frequency, so the more energy a single photon carries. That is why the line in the figure climbs to the right.
Past a certain size, one photon can knock an electron out of an atom. From there on the radiation is called ionizing, which covers part of the ultraviolet and all of the X-ray and gamma-ray range. Turning a radio transmitter up does not give anyone sunburn, because however many photons you add, each one is still too small.