RNA is made during transcription. During transcription, segments of DNA are used as templates to produce complementary RNA molecules. In prokaryotes transcription takes place in the cytoplasm. In eukaryotes transcription takes place in the cells nucleous.
Transcription requires an enzyme called RNA polymerase that is similar to DNA polymerase. RNA polymerase binds to DNA polymerase and separates DNA strands. The ability to copy a single DNA sequence into RNA makes it possible for a single gene to produce thousands of RNA molecules.