According to the Library of Congress website:
"During the late 1920s, early 1930s, and 1990s the Library of Congress acquired a large collection of Arabic script calligraphy sheets. This presentation exhibits 355 Arabic calligraphy sheets, ranging from the 9th to the 19th centuries. A majority of the calligraphy sheets were written on paper, however, a group of Qur’anic fragments from the 9th and 10th centuries were executed on parchment.
Calligraphy was a skill to be mastered, and it was heavily used to express religious sentiment and many other aspects of personal and cultural life. This collection showcases stunning examples of calligraphic art. In addition to the individual calligraphy sheets, this presentation includes essays on Ottoman and Persian calligraphic styles, an in-depth look at Qur’anic calligraphic fragments, and an essay discussing some of the Library’s notable Arabic script calligraphy sheets and illuminations."
Thanks to Annys from the Kingdom of Artemisia for the link.