Transcription is the transfer of genetic information from DNA (genes) to messenger RNA (mRNA). During transcription, RNA polymerase attaches to a gene's promoter sequence, "reads" the template DNA strand adding nucleotides to the 3' end of the growing mRNA molecule, and stops at a gene's terminator sequence. In eukaryotes, pre-mRNA is processed into mature mRNA with the addition of a 5' cap and poly-A tail, and the removal of introns (splicing).