The "Scholia on Homer" are not the work of a single author but a vast collection of ancient and medieval notes written in the margins of manuscripts of Homer's Iliad and Odyssey. This corpus was compiled over more than a thousand years, from roughly the 2nd century BCE to the 12th century CE, spanning the Hellenistic, Roman, and Byzantine periods.

The tradition began with the work of scholars at the Library of Alexandria, such as Zenodotus, Aristophanes of Byzantium, and especially Aristarchus of Samothrace. They produced critical editions and detailed commentaries, focusing on correcting the text, explaining difficult words, and interpreting the poems. A rival school of thought, which favored allegorical interpretation, developed at the Library of Pergamon. Later grammarians, including Didymus in the 1st century BCE and Aristonicus in the Augustan period, added further layers of commentary. These notes were continuously copied, summarized, and expanded over centuries, eventually being preserved in the margins of medieval manuscripts like the famous 10th-century Venetus A codex.

The scholia are critically important because they preserve the methods and debates of ancient scholars whose own works are now lost. They provide a unique window into how the Homeric poems were studied, taught, and edited in antiquity, documenting early variant readings and interpretations. According to modern scholars, this corpus is a foundational source for the history of literary criticism and textual scholarship, and it contains a wealth of information on ancient mythology, language, and culture.