Realms are the individual servers that are within Saico PVP.
There are 8 realms on SaiCo. Each Realm currently on Saico has another near identical realm. The pairs are...
Skeleton + Zombie
Blaze + Magma
Wither + Ghast
Witch + Ender
Skeleton Realm Edit
"Nothing more than Endless Piles of Bones, or so you may think... Beware..."
The Skeleton Realm is a generic faction server, with, of course, the Headhunting plugin added to all realms. Skeleton was the first realm that was on Saico.
Zombie Realm Edit
"A Demonic Plague has ravaged this realm, do you Dare to hunt in this Deadly Place?"
The Zombie Realm is the same as the Skeleton Realm, except with the added bonus of mcMMO Skills.
Wither Realm Edit
"A Desolate Wasteland full of Corruption due to its New Inhabitants..."
The Wither Realm has the added twist of OP Enchantments.
Witch Realm Edit
"Cast into Eternal Darkness by the Necromancers that inhabit the realm.."
The Witch Realm has Custom Enchantments made by SaiCoPvP.
Ender Realm Edit
"A Utopian Realm which was devastated by its Essences being used to bring destruction..."
The Ender Realm has the same experiences of the Witch Realm.
Blaze Realm Edit
"The Gates Of Nether have been unleashed Infesting this Hellish Realm with many demons..."
The Blaze Realm has the same experiences of the Skeleton Realm.
Magma Realm Edit
"Endless lakes of lava with many fierce Abominations lurking beneath its depths..."
The Magma Realm has the same experiences of the Zombie Realm.
Ghast Realm is nearly the same as Wither Realm, although it is being half used as a testing ground for new features. One of these features includes you being sent back to Spawn if you log out in enemy territory, or your Home being removed if it is set in enemy territory.
"The Hub is where all the great adventurers of the Warlock Guild begin their adventure to defeat the Evil Overlord"'
The Hub is where you will be every time you join the server. From there, you can chose one of the eight realms to travel to and begin playing on SaicoPvP. The Hub isn't a factions realm, and can only be used to go to the faction realms. More on the Hub can be found here .