The Nastaliq variant of Arabic script is a cursive script, written horizontally but at a sloping angle where the longer the sequence of characters is in a calligraphically-connected cluster, the taller it becomes. It has short verticals and long horizontal strokes. Due to the slope and calligraphic style, placement of nuqtas (dots) on the base characters is forced to vary quite a bit among different letters and even different forms of the same letter. Words are separated by a space.
The name (Nastaliq) is a composite of the names for the "Naskh" and "Taliq" styles of writing. Nastaliq is used in Afghanistan, India, Iran, and Pakistan. Because it is used for writing the Urdu language it is sometimes called Urdu script. However, it is also used for writing many other languages.
Nastaliq employs the Eastern Arabic-Indic digits. Standard Arabic-Indic digits are never used.
Nastaliq shares many aspects of the Arabic script. However, because of the particular challenges (sloping calligraphic style and nuqta positioning) with writing Nastaliq it has qualified to be listed as a separate script in ISO 15924.