This document discusses primer design for PCR. It defines a primer as a short DNA sequence that provides a starting point for DNA synthesis. It notes that DNA polymerase can only add nucleotides to an existing DNA strand. The document then covers criteria for primer design, including amplicon size, primer length and GC content, melting temperature, primer pair matching, annealing temperature, and 3' terminal properties. It also discusses potential problems like self-complementarity and provides examples of using software to design and analyze primers.