Short answers, pulled from the story.
The bulk of the Rigveda is generally dated to between c. 1500 and 1000 BCE, with some scholars proposing a wider range of c. 1900-1200 BCE. The earliest layers are among the oldest surviving texts in any Indo-European language. The codification of the collection is placed around c. 1200 BCE, in the early Kuru kingdom period.
The most studied Shakala recension of the Rigveda contains 1,028 hymns organized into ten books, or mandalas, with approximately 10,600 verses. The 1877 Aufrecht edition counted 10,552 individual verses (called rcas) and 39,831 padas, the smallest metrical unit.
The Rigveda was transmitted orally for many centuries through rigorous memorization techniques. The oral tradition prescribed structured enunciation, breaking Sanskrit compounds into stems and inflections with precise permutations of sound. The oldest surviving manuscripts were discovered in Nepal and date to around 1040 CE. Thirty manuscripts from the Bhandarkar Oriental Research Institute collection were added to UNESCO's Memory of the World International Register in 2007.
The chief deities are Indra, praised for slaying his enemy Vrtra; Agni, the sacrificial fire, whose name is the text's first word; and Soma, the sacred ritual potion, who receives the entire ninth mandala. Other major figures include the Adityas Mitra and Varuna, Ushas the dawn goddess, Savitr, Vishnu, and Rudra, alongside deified natural forces such as the sun, wind, and rivers.
Hymn 1.164.46 is one of the most widely cited passages in the Rigveda. It states that what is One is called by many names, including Agni, Yama, and Matarisvan. Max Muller coined the term "henotheism" specifically to describe the theology this verse expresses, distinct from the exclusive claims of monotheism in the Judeo-Christian tradition.
The first European translation of any portion of the Rigveda was a partial Latin rendering of 121 hymns by Friedrich August Rosen, published in London in 1830. Rosen worked from manuscripts brought back from India by Henry Thomas Colebrooke. Max Muller published the first printed full edition, in German, in 1849.