+Radioactivity is the spontaneous emission of particles and energy from an unstable [Atomic Nucleus](/wiki/Atomic_Nucleus). This natural process, a form of [Nuclear Decay](/wiki/Nuclear_Decay), reveals the profound transformations within matter and underlies the phenomenon of [Radiation](/wiki/Radiation).
+## See also
+- [Nucleus](/wiki/Nucleus)
+- [Isotope](/wiki/Isotope)
+- [Half-life](/wiki/Half-life)
... 1 more lines