Phagemids are used in a variety of biotechnology applications; for example, they can be used in a molecular biology technique called "phage display".
A phagemid can be replicated as a plasmid, and also be packaged as single stranded DNA in viral particles.
Similarly to a plasmid, a phagemid can be used to clone DNA fragments and be introduced into a bacterial host by a range of techniques, such as transformation and electroporation.
Inside the cell, the phage genome triggers production of single stranded phagemid DNA in the cytoplasm.
The displayed peptides and polypeptides are associated with the corresponding coding DNA within the phage particle and so this technique lends itself to the study of protein-protein interactions and other ligand/receptor combinations.