Energy barrier

An energy barrier was a barrier made of energy to keep individuals or objects in or out of an area.

Physical energy barriers
Physical energy barriers blocked solid matter and could be used defensively as force fields. A physical energy barrier was used by the Silurians to trap the occupants of Cwmtaff within itself. It was invisible to the naked eye, but could be seen if it was hit, or when excited by the Doctor's sonic screwdriver. The barrier was red in colour and did not allow people to pass through it. It did, however, allow rain to pass through. It could also block out light, making it seem as though it was night. (TV: The Hungry Earth)

Holographic energy barriers
Holographic energy barriers used energy in the visible spectrum to alter what was seen. The Terileptils used holographic energy barriers to create the illusion of additional walls in a house. The Fifth Doctor was able to dismantle one using his sonic screwdriver, allowing him to his companions to simply step through it. (TV: The Visitation)

Time energy barrier
A time energy barrier was a visible barrier which appeared as a dense fog. Those who entered the fog, such as Jackie and Joe Hargreaves, would always exit it the same way from which they had come. Leet, a Dellacoi, created a time energy barrier over Cardiff when it lost control of its search units. The barrier meant that nobody, including both Torchwood Three and UNIT, could get in or out of the city. The barrier also blocked mobile phone signals but appeared to let rain through. (PROSE: Bay of the Dead)