The Standard Babylonian version of the Epic of Gilgamesh is arranged in 12 tablets. This edition is the best-known long form of the poem and was written in literary Akkadian, drawing on much older Sumerian and Babylonian traditions.
The version is commonly associated with the scholarly scribe Sîn-lēqi-unninni and was compiled during the second millennium BCE, though surviving copies are later. Its opening theme presents Gilgamesh as the king who experienced and learned about the world. The narrative follows his friendship with Enkidu, their heroic exploits, Enkidu’s death, and Gilgamesh’s search for an escape from mortality.
Tablet 12 is unusual. Rather than continuing the tightly structured story of the first 11 tablets, it closely adapts an earlier Sumerian tale about Gilgamesh and the Netherworld. Because of that mismatch, readers may encounter references to an “11-tablet epic” as well as the standard “12-tablet” edition. For this question, 12 is the canonical answer.