Force field

Overview
Forcefields are designed to prevent an individual or their weapons fire from passing through a cirtain point, much like Shields on Starships. They are ustilized by many races as security barriers.

Ancient
The Ancients used forcefields to protect their Stargates and to seal people into cirtain sections of their ships. They are also used in their cells of Atlantis and can prevent even Wraith from escaping.

Tok'ra
The Tok'ra use an advanced form of one-way forcefield to keep their prisioners inside their cells whilst allowing weapons fire to enter the cell should it be neccesary.

Tollan
The Tollan force fields are used to protect key areas of the government buildings.