Role in TV show/Comics
In the comics the Veil is Dimensional separating energy, with 12 portals from Earth to Meridian in it, which Guardians had been tasked to close with the help of a map, which showed to location of the portals. The Guardian instead traveled to Meridian with the help of the portals, and worked with the rebellion to defeat Prince Phobos. After Elyon took control over Meridian as Queen, Kandrakar lowered the veil.
In the TV Series, The Veil is a Pink/Purple energy, that can contain things of any size.
In season 1 The Veil was introduced by Yan Lin as magic created to keep Meridians evil from spreading to the other worlds.She tasked the Guardians with closing all the portals that open, so the evil does not escape. They soon find out that they will not have an easy time closing all the portals.
Only 3 things can open holes in the veil:
Season 2After the defeat of phobos the Guardians are summoned to Kandrakar, via a pink portal, there they see The Veil.
During one of Nerissa's attacks on Kandracar, the congregation decides to create a new Veil for protection. The Mistakenly invite Nerissa (Disguised as the Mage) into their mystic-link, giving her the power to capture them all in the new Veil. This new Veil could only be destroyed by the Heart of Meridian, which Nerissa had. Once the power was returned to Elyon she destroyed the new Veil, an freed the congregation.