Portals are artificially created doorways used for transit on the Sphere.
Portals appear all around the Sphere and is mostly used to travel between vast levels of the Sphere. Portals in the game can transport the player from one area to another instantly; portals can be looked and shot through and can also be travelled in reverse.
Portals are usually opened by a device possessing mutiple rings around it which start to spin violently before emitting electrical discharge but both Mother and Keepers have showed to be able to open them at will without the use of any visible device. Sometimes portals appear in crates. These portals do not possess blue/orange energy around them and their purpose on the Sphere is unknown.