Engineered transmembrane pores.

•Nanopores are making a strong impact in both basic science and biotechnology.•Protein nanopores can be engineered with precision and are preferred for most applications.•Recent years have seen an increase in the diversity of pores through the exploitation of new structures.•Diversity has also been increased by the application of a wider variety of engineering techniques.•Emerging applications require continued efforts to obtain pores with specified properties.