Gestell (or sometimes Ge-stell) is a German word used by twentieth-century German philosopher Martin Heidegger to describe what lies behind or beneath modern technology. He introduced the term in 1954 in his The Question Concerning Technology (the text is based on the lecture "The Framework" ("Das Gestell"), which he first presented on December 1, 1949, in Bremen).
Heidegger applied the concept of Gestell to his exposition of the essence of technology. He concluded that technology is fundamentally Enframing. As such, the essence of technology is Gestell. Indeed, "Gestell, literally 'framing', is an all-encompassing view of technology, not as a means to an end, but rather a mode of human existence".
In defining the essence of technology as Gestell, Heidegger indicated that all that has come to presence in the world has been enframed. Thus what is revealed in the world, what has shown itself as itself (the truth of itself) required first an Enframing, literally a way to exist in the world, to be able to be seen and understood. Concerning the essence of technology and how we see things in our technological age, the world has been framed as the "standing-reserve." Heidegger writes,
Enframing means the gathering together of that setting-upon which sets upon man, i.e., challenges him forth, to reveal the real, in the mode of ordering, as standing-reserve. Enframing means that way of revealing which holds sway in the essence of modern technology and which is itself nothing technological.
Furthermore, Heidegger uses the word in a way that is uncommon by giving Gestell an active role. In ordinary usage the word would signify simply a display apparatus of some sort, like a book rack, or picture frame; but for Heidegger, Gestell is literally a challenging forth, or performative "gathering together", for the purpose of revealing or presentation.