Transduction is the process of transfer of a portion of DNA from one bacterium to another via a Bacteriophage. Transduction may be classified as generalized or restricted depending on the material transferred via transduction.
Generalized transduction involves a segment of donor DNA
Restricted transduction occurs when only a particular trait is transferred.
Transduction involves both chromosomal DNA and extrachromosomal DNA(episomes, plasmid). Transduction is the most common mechanism of gene transfer among prokaryotes which also helps in genetic mapping.