Portals are the main way PPC agents travel through the multiverse. They are generated by consoles, and can be opened using a remote activator. It is generally considered impossible to portal into HQ without PPC technology, but there have been exceptions: in 2006 the Black Cats deactivated the shields that prevent outside portalling, and the Sue invaders in 2003 and 2008 somehow bypassed the shields as well.
Forms of the verb "to portal" are portaling/portaled in American usage or portalling/portalled in British/Commonwealth usage. This page happens to feature British usage.
In most cases, portals appear as blue doorways in space and time. When an agent opens one, there is "an odd hum," and a glowing dot appears in the air in "a rather unimpressive flicker." This lengthens into a horizontal line generally 1-2 meters long, which then stretches vertically in both directions to form the oblong door effect.
However, this imagery is not an intrinsic part of the portal. Rather, it was added to the technology by Makes-Things early on, at the insistence of the now-defunct Department of Health and Safety, to deal with the issues arising from invisible portals, particularly the danger of half a person passing through while the other half remains behind. Thus, some portals have different activation effects: some show the view on the far side, some do not; some are rectangular, some are oval or round; some have different colors, such as Logan and Entropy's grey one; and in one case, Nyx Nightingale used a portal with no visible manifestation whatsoever. The links between the many sections of HQ are similarly non-visible portals, their sides matching up with the corridor walls.
Portals are, at their hearts, simply stabilised plotholes. The Flowers engaged in experimentation with plotholes since before they left Origin, expanding their Headquarters through stabilised natural plotholes. Their first encounter with the rogue plothole generators they dubbed 'Merry Pseudos' gave them the information they needed to create their own.
Plotholes and portals are written into existence. Initially this was done on a case-by-case basis, being a long and laborious process. Makes-Things introduced electronic computers to the mix, allowing portals to be generated en masse. He also induced a thermo-electric current across each portal, making them self-powering. Failing to include an off-switch in the initial prototype led to the Cascade.
Because of their written nature, PPC-generated portals can only lead into or out of Word Worlds. This is not the case for naturally-occurring plotholes. Due to the ease of creating written portals, compared to the long and uncertain method of waiting for them to appear naturally and hoping a stabiliser can reach them in time, only a handful of PPC HQ's structural portals lead anywhere other than Word Worlds. The rooms beyond them are Reality Rooms.