The BioBrick® Assembly method is part of the BioBrick synthetic biology approach, in which a bioengineering focus has been applied to building novel biological systems. In this approach, DNA fragments encoding proteins, promoters, ribosome binding sites, etc., have been standardized and are contained in a "parts" registry of plasmids with identical restriction sites flanking the "payload" of the part. By employing standardized flanking sites that are not contained within the coding sequence of the part, they can be ligated in any order to create a novel "device". By choosing restriction sites with compatible ends that destroy the recognition site when ligated to one another, parts can be combined together and the original flanking sites re-used for the next round of assembly. Despite the limitations of introducing a sequence scar for every ligation event and the multiple rounds of assembly required to fabricate a device, a wide assortment of exciting systems have been designed and built.