+An [Excitation](/wiki/Excitation) describes a system moving from its stable [Ground State](/wiki/Ground_State) to a higher, less stable energy level. This shift often involves absorbing [Energy](/wiki/Energy) and represents a temporary active state.
+## See also
+- [Ground State](/wiki/Ground_State)
+- [Energy](/wiki/Energy)
+- [Phonon](/wiki/Phonon)
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