Garganta|黒腔 (ガルガンタ)|Garuganta|Spanish for "Throat", Japanese for "Black Cavity" is how Arrancars and Hollows move to and from Hueco Mundo. It literally tears open the dimensional fabric separating the worlds, revealing a tunnel of whirling, torrential energy that must be focused and solidified to create a discernible pathway. It is primarily used by Hollow and Arrancar, but some other characters have used it through different means.
There is also another use for Garganta, only shown once: Garganta Broadcast, a visual broadcast similar to a television screen, created by using individual Garganta portals. Ulquiorra Cifer does this in order to show the current predicament of Orihime Inoue's friends (Ichigo Kurosaki, Tōshirō Hitsugaya and Rangiku Matsumoto) fighting their respective battles. It is unknown if he could create as many as desired, or if three broadcasts are his limit.
All Menos class Hollows and Arrancar are capable of opening a Garganta. In most cases, it opens with the distinctive segmented pattern, but in the case of the first Gillian-class Menos to appear in Karakura Town, and those at the Sōkyoku Hill, an opening is simply torn in the sky as if it were cloth, leaving jagged edges.
Also, Urahara Kisuke has demonstrated the ability to use the technique. The incantation he used is: "My right hand is the stone that bridges worlds. My left hand is the blade that binds reality. The black-haired shepherd is hung from a chair. Stratus clouds come, and I strike down the ibis".
More recently, Captain Mayuri Kurotsuchi has acquired the ability to use Garganta through extensive research whilst trapped in Hueco Mundo.