Hologram

Holography is the science of producing holograms, an advanced form of photography that allows an image to be recorded in three dimensions. The technique of holography can also be used to optically store and retrieve information.

The Ancients had technology to make a solid holographic guardian and holographic sword, as well as a fully interactive teaching program and most probably other similar programs. The Asgard also developed a holographic pedastel to allow them to communicate with others by projecting holograms onto nearby ships or broadcasting them to other projectors light-years away.

Ancient
Ancient holograms are the most advanced, besides the ability to project over long distances, later versions could create sound like the Asgard versions, but unlike the Asgard holograms, Ancient ones can become solid and even create realistic physics simulation such as the holographic sword (weight, friction, etc.) Ancient ships also possess holographic HUDs and can project holograms with sound onto other ships even when traveling at 99.9% light speed, although this speed does hinder their ability to receive sound.

Asgard
The Asgard can create holograms that can project themselves, with sound, over long distances (for example, a planet's surface to a ship.) They can also be transmitted and then recreated from another projector to work as a 3D communicator.

Goa'uld
The only Goa'uld holograms seen are the HUDs on their Tel'taks and the Peltacs of Ha'taks. After Anubis stole knowledge from Thor using a Mind probe, him and Baal began to incorporate Asgard holographic technology onto their ships.