Epigenetics: How does it work?

Why hasn't Epigenetics been heard before? It is probably because it wasn't detected until recently and also because it is a field still in discovery. Epigenetics does not alter the sequence of DNA, so how is it heritable? The epigenetic modifications are the mechanisms by which most living beings are different. These include DNA methylations (or addition of a methyl group); post-translational histone modifications, such as methylation, acetylation, ubiquitination and phosphorylation; chromatin remodeling; histone variants and noncoding RNAs. These concepts will be introduced very soon, but first it is really important to understand what histones are, how are they related to DNA and the processes involved in the formation of proteins from DNA.

For more more informations about histones:
http://www.whatisepigenetics.com/histone-modifications/

http://202.97.205.78/hhmd/Images/histone_modifications_big.jpg