A large portion of relevant modules/templates have now been switched to cargo. Various usages of SMW throughout the wiki need to be replaced by the new functions, in particular item tables. If some pages do not show up but contain no errors, please null-edit them. To see how you can help with the port check out Path_of_Exile_Wiki:To-do_list/SMW_migration (and leave a comment on the talk page if you have questions).
A portal is an entity that allows instant travel to and from the town in the act where it is created or the previous town if the current town is unvisited. The standard blue portal appearance can be changed by purchasing a Portal Effect.
Portals created by players
Player-created portals can be used to travel to town unlimited times by any party members. However, it will disappear once the creator uses it from the town-side. Other party members can use the town-side portal unlimited times. Portals will automatically disappear after the instance they are linked to has expired. The expiration time for instances is 8 minutes for normal instances and 15 minutes for "hub" instances (instances that lead to more than one instance, eg. Mud Flats which leads to Fetid Pool and Submerged Passage). A portal will not expire as long as the instance it is linked to is prevented from expiring (eg. a player stays in it).