A hologram is an image obtained through a photographical method. It enables us to see a virtual object in its three dimensions (height/width/depth).
Some physicists think the universe in which we live could be a huge hologram.
What appears to us as a three-dimensional universe would, in fact, be made of only two dimensions.
Just like the characters on a TV screen, our universe would be a plane surface that only gives an impression of depth.
The depth of the universe would in fact be an illusion, a sense of elevation and depth produced by the projection of an event that would have occurred in another cosmos.