mRNA, is used to transcript DNA codes from DNA molecules and then later exits the nucleus via nuclear pore, then moves to the ribosome. Then, tRNA is activated to bring specific amino acid to the ribosome for translation. Ribosome, which is the site of synthesis of proteins, is composed of rRNA and ribosomal proteins.
A codon is a three-base sequence (three nitrogen bases in a row) on mRNA. An anticodon is a three-base sequence on tRNA. It matches the codon.