Dž is a digraph that corresponds to the letter Dzhe (Џ/џ) of the Serbian Cyrillic alphabet.
Note that when the letter is the initial of a capitalised word (like Džungla or Džemper, or personal names like Džemal or Džamonja), the ž is not uppercase.
In Gaj's Latin alphabet (used for Serbo-Croatian), when the text is written vertically rather than horizontally (on signs, for instance), dž is written horizontally as a single letter; in particular, dž occupies a single square in crossword puzzles.
Unicode representations of the letter are very rarely used in digital media, which tends to favor the corresponding two-character combinations.
Manufacturers of computer keyboards and typewriters for Croatian users typically do not provide a single key for the letter.