Even the most powerful sorcerers can get quite frustrated when they want to jump into their portal to travel to another part of their realm, and the portal fades away just in front of them. However, in the same way as laziness of some travelling mage or druid allowed development of portal, similarly some wise spellcaster decided that it should be possible to extend duration of already existing portal. And behold, stabilize portal spell was born. It is possible to renew a portal repeatedly, allowing sort of permanent long-range connections, as long as there is someone to care about them.

See also: portal