One of the most powerful laboratory tools used in biotechnology is the engineering of specific genes. This chapter will cover methods of cutting double-stranded DNA, inserting it into plasmids, and sealing the plasmids. The use of plasmids allows for their amplification via prokaryotes such as E. coli. After an incubation period measured in hours, the E. coli are lysed and plasmid DNA is harvested by a series of separation that will be technically described in detail. The chapter will conclude with a discussion of how the amplified plasmids are quantified.