RNA editing is a major epigenetic regulator of gene expression, involved in thefine-tuning of cellular responses sustaining cellular homeostasis.• RNA editing systems fall into two general classes: insertion/ deletion andsubstitution.• There are several types of RNA editing, among which the deamination ofAdenosine (A) to Inosine (I) or Cytidine (C) to Uridine (U) is the most commontype in mammals.• Adenosine deaminases acting on RNA (ADAR), and (apolipoprotein B mRNAediting enzyme catalytic polypeptide-like (APOBEC) enzyme families,catalyzed the major type of RNA editing in mammals (A-to-I and C-to-U,respectively).• RNA editing may be advantageous for adaptation to changing environments.• Several studies have associated RNA editing with disease conditions, includinga number of neurodegenerative disorders.• Medical tools have been developed based on RNA editing.