Transcription is the first step in gene expression. RNA strands are constructed by cellular enzymes that read the genetic code of a single DNA strand, and synthesize a complimentary RNA strand. Usually, particularly in eukaryotic cells, such as humans, plants and animals, transcription is initiated by a complex of enzymes including RNA polymerase, which bind to the DNA strand at a specific location known as the promoter or enhancer region. Initiation of transcription is often a complex process that requires the presence of a number of proteins called transcription factors. These proteins bind to the DNA strand and interact with one another, either turning transcription on or off, depending on the combination and types of transcription factors present.
Transcription results in the formation of a single strand, or polymer, of ribonucleotides (RNA), the order of which is based on the order of the chain of deoxyribonucleotides that constitute the "template" DNA strand.
Transcription is part of the process by which proteins are made. The next step in the process is translation of the RNA code to an amino acid chain, resulting in a protein.