The Holographic Principle states that the everyday reality that we experience (including you and me) is a projection from somewhere else, i.e. the boundary of the universe. The 'projector' (similar to "R2D2's projector in the picture above) is a two dimensional surface where everything exists. The projections (like Princess Leia's hologram above) is in three-dimensions. In a sense, we are really two-dimensional pixels living on that distant surface who are projected in three-dimensions.
Strange as this may seem, physicists may have found an opportunity to confirm this via a device that was built for another purpose. They take advantage of the fact that something with three dimensions (an object with length, width and height like a box) can hold more stuff than something that has only two dimensions (an object with just length and width like a sheet of paper). A two-dimensional pixel when projected in three-dimensions will appear more blurred than the original and if such blurring is detected, then this would support the view that we are holograms.
[Personal speculation: It would take a longer explanation but it occurs to me that if we are holographic projections from a two-dimensional surface, by analogy, one possible way from the Universe to end is to evaporate, or collapse into an infinitely dense point, i.e. a space-time singularity sort of like the fate described in the Big Crunch but in a different way...]