The Epic of Gilgamesh is, as the title suggests, an epic poem. In fact, some say The Odyssey and The Aeneid were influenced by The Epic of Gilgamesh, which is the oldest surviving complete story currently known (although in many ways it is still considered incomplete). What comes down to us as The Epic of Gilgamesh comes from different versions of the story, originally told orally, transcribed onto tablets between roughly 2100 B.C.E. to 1200 B.C.E.
The Epic of Gilgamesh was written in the ancient civilization of Sumer, within Mesopotamia (modern day Iraq), in the Ancient Sumerian language. As such, it is read as a work of translation. Although much of the original context is lost to history, many of the themes and plot points—loss of innocence, nature versus civilization, a great flood—will strike the reader as familiar and relatable. Indeed, the description of a great flood and the tale of a loss of innocence will strike readers of the Bible as familiar: some scholars say the Bible was influenced by The Epic of Gilgamesh.
The Epic of Gilgamesh is thus an incredibly influential story worth studying in its own right, both because of its place in history and because of the influence it has had on other widely-read poems and stories.