So elongation is basically the process where our RNA polymerase actually synthesizes the RNA molecule. So once RNA polymerase unwinds the DNA it creates a bubble that is commonly known as our transcription bubble that is shown in the following diagram. So basically what the transcription bubble is it's a region where our two single strands of DNA have been separated and are now exposed. Now notice only one of these DNA strands is actually used to synthesize our RNA molecule. So to see what we mean, let's take a look at the following diagram. So we can imagine that our initiation factors, these proteins are moving across our DNA.