A super-massive black hole, the Galactic Centre was situated at the very center of the galaxy, within the Deep Core region. The singularity was the crux of rotation of the entire galaxy, including its approximately 400 billion stars. Exerting a gravitational pull greater than that of a thousand stars, the Galactic Centre sucked in and crushed all nearby matter and devoured light and energy, with endless plumes of gas spiraling into the black hole. The forces of the Galactic Centre wreaked havoc with the fabric of space itself, causing eddies that rippled away from the black hole and out into the Deep Core.
The black hole's forces affected the stars that were far enough away to avoid the black hole's pull, though the effect was smaller on more distant stars. As a result, the Galactic Centre caused the stars of the Deep Core to constantly shift. The constant movement of stars led the hyperlanes of the region to change daily, making travel within the Deep Core a risky task that required constant remapping.
Though the Galactic Centre was the true center of the galaxy, the Core World of Coruscant—which was some distance from the black hole—became the galactic capital and was designated with the coordinates 0,0,0 due to its status as the effective center of the Galactic Republic. As such, Coruscant marked the center of astrogation mapping.
Shortly after the soldier Hazram Namir joined the Rebel Alliance's 61st Mobile Infantry, fellow rebel trooper Gadren educated him about the nature of the universe, including the black hole at the galaxy's center. Namir recalled Gadren's words during the Battle of Hoth in 3 ABY.
In the new Star Wars canon, the Galactic Centre was first mentioned, albeit indirectly, in the Guide to the Galaxy department within the thirty-fourth issue of the magazine Star Wars: Build the Millennium Falcon, published in 2015. It was later identified in the Guide to the Galaxy section of the series' thirty-sixth installment.