The Yashts are a collection of twenty-one hymns in the Younger Avestan language. Each of these hymns invokes a specific Zoroastrian divinity or concept. Yasht chapter and verse pointers are traditionally abbreviated as Yt.
The word yasht derives from Middle Persian yašt (“prayer, worship”) probably from Avestan (yašta, “honored”), from (yaz, “to worship, honor”), from Proto-Indo-European *yeh₂ǵ-[1] or *Hyaǵ-,[2] and several hymns of the Yasna liturgy that "venerate by praise" are—in tradition—also nominally called yashts. These "hidden" Yashts are: the Barsom Yasht (Yasna 2), another Hom Yasht in Yasna 9–11, the Bhagan Yasht of Yasna 19–21, a hymn to Ashi in Yasna 52, another Sarosh Yasht in Yasna 57, the praise of the (hypostasis of) "prayer" in Yasna 58, and a hymn to the Ahurani in Yasna 68. Since these are a part of the primary liturgy, they do not count among the twenty-one hymns of the Yasht collection.
All the hymns of the Yasht collection "are written in what appears to be prose, but which, for a large part, may originally have been a (basically) eight-syllable verse, oscillating between four and thirteen syllables, and most often between seven and nine."[3]
Most of the yazatas that the individual Yashts praise also have a dedication in the Zoroastrian calendar. The exceptions are Drvaspa and Vanant.
The twenty-one yashts of the collection (notes follow):
| Yasht # | title / nominally invokes | in praise of | extent | |
| 1. | Ohrmazd Yasht | 33 verses | ||
| 2. | Hapt Amahraspand Yasht | the seven Amesha Spentas | 15 verses | |
| 3. | Ardawahisht Yasht | Asha Vahishta of "Best Truth" | 19 verses | |
| 4. | Hordad Yasht | Haurvatat of "Wholeness" and "Perfection" | 11 verses | |
| 5. | Aban Yasht | 132 verses | ||
| 6. | Hwarshed Yasht | Hvare-khshaeta of the "Radiant Sun" | 7 verses | |
| 7. | Mah Yasht | Maonghah of the "Moon" | 7 verses | |
| 8. | Tishtar Yasht | 62 verses | ||
| 9. | Drvasp Yasht | Drvaspa, guardian of horses | 33 verses | |
| 10. | Mihr Yasht | Mithra of "Covenant" | 145 verses | |
| 11. | Srosh Yasht | Sraosha of "Obedience" | 23 verses | |
| 12. | Rashn Yasht | Rashnu of "Justice" | 47 verses | |
| 13. | Fravardin Yasht | the Fravashis | 158 verses | |
| 14. | Warharan Yasht | Verethragna, "Smiter of resistance" | 64 verses | |
| 15. | Ram Yasht | the "good" Vayu | 58 verses | |
| 16. | Den Yasht | Chista, "Wisdom" | 20 verses | |
| 17. | Ard Yasht | Ashi of "Recompense" | 62 verses | |
| 18. | Ashtad Yasht | khvarenah, the "(divine) glory" | 9 verses | |
| 19. | Zam Yasht | see note below | 97 verses | |
| 20. | Hom Yasht | 3 verses | ||
| 21. | Vanant Yasht | 2 verses |
| a. | The Yashts did not originally have titles. These were assigned at some time during the Common Era, and hence reflect the Middle Persian forms of the divinities' names. | |
| b. | Several Yashts are—despite their names—hymns to other divinities or concepts.
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| c. | Yashts 1–4 are "mediocre, meaningless texts, composed in incoherent language; they probably result from a very late expansion of the Yašt collection." | |
| d. | Yasht 9 to Drvaspa has a number of verses that are originally from Yasht 5, the hymn to the waters. | |
| e. | Yashts 11 and 12 are respectively hymns to Sraosha and Rashnu, but are to some extent also an extension of Yasht 10, the hymn to Mithra. Sraosha and Rashnu are both attendants of Mithra. | |
| f. | There is also a "hidden" Yasht to the waters at Yasna 38. | |
| g. | Yasht 5 (in praise of Aredvi Sura Anahita) and Yasht 17 (to Ashi) share a number of verses. It is not possible to determine which of the two is the original. | |
| h. | The Avesta has two hymns that were later titled Hom Yasht. The original is part of the Yasna liturgy and hence not counted as a Yasht. The other, Yasht 20, is a duplicate of the three verses of Yasna 9–11. | |
| i. | Vayu, divinity of wind and atmosphere, is a dual divinity: part benevolent and part malign. |