What is radiation , in really simplified words please
Particles (or waves) with energy that come from a source and travel through some material or through space are called radiation. Sunshine is one of the most familiar forms of radiation. Light and sound are types of radiation. The type of radiation which produce new charged particles in matter is called ionizing radiation. Radiation that has enough energy to move atoms in a molecule around or cause them to vibrate, but not enough to remove electrons, is referred to as "non-ionizing radiation." Radiation that falls within the ionizing radiation range has enough energy to remove tightly bound electrons from atoms, thus creating ions. Both ionizing and non-ionizing radiation can be harmful to organisms and can result in changes to the natural environment. There are different types of radiation. It depends on type of particles which come from a source (electrons, protons, alpha, etc...) and their energy.
X-rays and gamma rays, like light, represent energy transmitted in a wave without the movement of material, just as heat and light from a fire or the sun travels through space. X-rays and gamma rays are virtually identical except that X-rays are generally produced artificially rather than coming from the atomic nucleus. But unlike light, X-rays and gamma rays have great penetrating power and can pass through the human body. Mass in the form of concrete, lead or water are used to shield us from them.
Alpha particles consist of two protons and two neutrons, in the form of atomic nuclei. They thus have a positive electrical charge and are emitted from naturally-occurring heavy elements such as uranium and radium, as well as from some man-made elements. Because of their relatively large size, alpha particles collide readily with matter and lose their energy quickly. They therefore have little penetrating power and can be stopped by the first layer of skin or a sheet of paper.
Beta particles are fast-moving electrons ejected from the nuclei of many kinds of radioactive atoms. These particles are much smaller than alpha particles and can penetrate up to 1 to 2 centimeters of water or human flesh. They can be stopped by a sheet of aluminium a few millimeters thick.
Cosmic radiation consists of very energetic particles, mostly protons, which bombard the Earth from outer space. It is more intense at higher altitudes than at sea level where the Earth's atmosphere is most dense and gives the greatest protection. Neutrons are particles which are also very penetrating. On Earth they mostly come from the splitting, or fissioning, of certain atoms inside a nuclear reactor. Water and concrete are the most commonly used shields against neutron radiation from the core of the nuclear reactor.