The article discusses the molecular signals that underlie epigenetic states, which are responsible for the establishment, maintenance, and reversal of metastable transcriptional states in cells. Epigenetic signals can be categorized into *cis* and *trans* types. *Cis* signals are physically associated with the DNA sequence they regulate and are inherited along with the chromosome, while *trans* signals are self-propagating and maintained through feedback loops involving transcription factors (TFs). TFs play a crucial role in establishing epigenetic states, and their activity can be reinforced by histone modifications and DNA methylation. The maintenance and spreading of *cis* epigenetic states involve feedback loops and the interaction between histone modifiers and binders. DNA methylation and histone modifications can be transmitted through cell division, but the mechanisms for their transmission and maintenance are still under investigation. The article also highlights the reversible nature of epigenetic states, which allows for transitions between different states in response to appropriate signals. Finally, the authors discuss the potential applications of epigenetic research in understanding brain function, stem cell function, and aging.The article discusses the molecular signals that underlie epigenetic states, which are responsible for the establishment, maintenance, and reversal of metastable transcriptional states in cells. Epigenetic signals can be categorized into *cis* and *trans* types. *Cis* signals are physically associated with the DNA sequence they regulate and are inherited along with the chromosome, while *trans* signals are self-propagating and maintained through feedback loops involving transcription factors (TFs). TFs play a crucial role in establishing epigenetic states, and their activity can be reinforced by histone modifications and DNA methylation. The maintenance and spreading of *cis* epigenetic states involve feedback loops and the interaction between histone modifiers and binders. DNA methylation and histone modifications can be transmitted through cell division, but the mechanisms for their transmission and maintenance are still under investigation. The article also highlights the reversible nature of epigenetic states, which allows for transitions between different states in response to appropriate signals. Finally, the authors discuss the potential applications of epigenetic research in understanding brain function, stem cell function, and aging.