What two colors are the portal ends created by the portal gun?

Portal’s portal gun creates blue and orange portal ends.

The two colors identify the linked openings that the Aperture Science Handheld Portal Device places on valid surfaces. Entering either portal sends Chell or a suitable object out of the other, so blue is not permanently an entrance and orange is not permanently an exit. Their roles depend on how the player uses them.

The color pairing is important for quick visual recognition. In a busy test chamber, players can immediately distinguish the two ends and understand which surfaces are connected. The game’s physics preserve momentum through the connection, while the exit portal’s orientation determines the direction in which the player or object emerges.

The blue-and-orange idea was inherited from Narbacular Drop, the 2005 student game whose portal concept inspired Valve’s Portal team. Portal retains that color distinction while changing the setting, story, and many mechanics. A common mistake is to treat the colors as different portal types; in the original game, they are two matching ends of one connection. Portals may still be restricted by surfaces, glass, liquids, moving objects, and other rules.