The Iliad originated within a rich oral tradition, likely dating back to the Mycenaean period (circa 1600–1100 BCE). Bards, or aoidoi, performed it from memory, relying on formulaic expressions and epithets like "swift-footed Achilles" to aid recitation and flexibility. Centering on the Trojan War, which may have roots in real Late Bronze Age events, the Iliadbecame a vessel for preserving cultural values, religious beliefs, and shared history. Oral-formulaic techniques allowed the story to adapt with each performance while maintaining its core themes.

The Iliad was passed down orally for centuries before Greek writing systems re-emerged in the 8th century BCE. However, the story is set in the Late Bronze Age, several centuries before Greek writing began. During the "Greek Dark Ages" (circa 1100–750 BCE), without formal writing systems, the Iliad continued through oral transmission, with each generation of bards adapting it to reflect contemporary values. By the time it was written down, the Iliad had already been reshaped by centuries of storytelling, blending older themes with the cultural shifts of early Greek society.

As an orally transmitted work, the Iliad adapted differently in various Greek regions. In Thessaly, known for its association with Achilles, the local versions emphasized his heroic status, amplifying his exploits. In Asia Minor, near the historical site of Troy, Trojan characters like Hector were viewed more sympathetically, highlighting his bravery and loyalty. Western Greece, particularly Ithaca, focused on Odysseus’s intelligence, reflecting admiration for resourcefulness. In Sparta, themes of martial valor and loyalty were emphasized, while Ionia placed greater focus on the gods and their interactions with humans, aligning with philosophical interests in fate and divine will.

Over time, the Iliad incorporated new elements from mythological and philosophical traditions. As Greek society evolved, so did the themes of the epic, with concepts like honor, fate, and moral order becoming particularly resonant in the Archaic period. Scholars also believe that the Iliad underwent structural changes, with episodes added or emphasized to align with shifting views on heroism, warfare, and leadership.

The oldest written versions of the Iliad are believed to date back to the 8th century BCE, though these original manuscripts no longer exist. Likely transcribed in Ionia in the Ionian Greek dialect, the first written version may have been commissioned by aristocratic patrons seeking to preserve the story as literacy grew. These early transcriptions served as a foundation for later standardized versions.

The authorship of the Iliad is traditionally attributed to Homer, who is said to have lived in the 8th century BCE. However, the question of Homer’s existence remains debated. Some scholars argue that Homer may have been a symbolic figure representing the collective tradition of Greek epic poetry, while others contend that he was a historical poet who compiled the Iliad from oral versions. By the Classical period, Homer was celebrated as the foundational poet of Greek culture, his works considered essential to Greek identity. Modern scholars, however, recognize that the Iliad likely resulted from multiple contributors across generations, with Homer’s name reflecting a longstanding oral tradition rather than a single author.

The Iliad is a profound fusion of myth, history, and artistic invention, transformed through oral transmission and shifting cultural landscapes into a foundational text in Western literature. Though attributed to Homer, the Iliad embodies centuries of Greek heritage and stands as an enduring exploration of the human condition, shaped by storytelling, adaptation, and, ultimately, transcription into written form.