Another way of looking at epigenetics is like this.
While traditional genetics describes the way the DNA sequences in our genes are passed from one generation to the next, epigenetics describes passing on the way the genes are used. To make a computer analogy, think of epigenetics as metadata, information describing and ordering the underlying data. If you own an MP3 player for example, it will contain a lot of data, the MP3 files. Think of these as analogous to genes. But you will also probably have playlists or you may play tracks by artist or genre. This information, playlist, artist, genre etc. is metadata. It determines which tracks are played and in what order, and this is what epigenetics is to genetics. It is a set of processes that effects which genes are switched-on, or “expressed”, as molecular biologists would say.