The process by which genes are controlled. When they are turned on or
off, how much to make. Often has a cascading effect.
Transcriptional regulation
Control output of transcripts before transcription occurs.
Transcription factors 
Epigenetic (histone) modifications 
Post-transcriptional regulation
Control what happens to transcripts after they are made.
Splicing 
non-coding RNAs (ncRNAs) 