Radioactivity refers to the particles which are emitted from nuclei as a result of nuclear instability. It is also known as a decomposition process.
Radioactivity was first discovered in 1896 by the French scientist Henri Becquerel.
The three main types of radioactivity are alpha radiation, beta radiation, and gamma radiation. Alpha radiation consists of helium nuclei, while beta radiation consists of electrons or positrons. Gamma radiation is a high-energy form of electromagnetic radiation.