mRNA (messenger RNA) is a type of single-stranded RNA that’s synthesized from a DNA template during the process of transcription. 

mRNA plays an integral role in protein synthesis. Its main function is to carry instructions for making protein from the DNA in the nucleus to the ribosomes in the cytoplasm. Each mRNA molecule encodes the information required to assemble one protein. On binding to the ribosome in the cytoplasm, the ribosome uses the information in the mRNA to assemble proteins during a process known as translation.