DNA printing can thus be used to produce DNA parts, which are defined as sequences of DNA that encode a specific biological function (for example, promoters, transcription regulatory sequences or open reading frames). However, because oligonucleotide synthesis typically cannot accurately produce oligonucleotides sequences longer than a few hundred base pairs, DNA assembly methods have to be employed to assemble these parts together to create functional genes, multi-gene circuits or even entire synthetic chromosomes or genomes. Some DNA assembly techniques only define protocols for joining DNA parts, while other techniques also define the rules for the format of DNA parts that are compatible with them. These processes can be scaled up to enable the assembly of entire chromosomes or genomes. In recent years, there has been proliferation in the number of different DNA assembly standards with 14 different assembly standards developed as of 2015, each with their pros and cons.  Overall, the development of DNA assembly standards has greatly facilitated the workflow of synthetic biology, aided the exchange of material between research groups and also allowed for the creation of modular and reusable DNA parts.
The various DNA assembly methods can be classified into three main categories – endonuclease-mediated assembly, site-specific recombination, and long-overlap-based assembly. Each group of methods has its distinct characteristics and their own advantages and limitations.