3D TV, or three-dimensional television, refers to a technology that was designed to provide viewers with a sense of depth and three-dimensional perception while watching television content. The idea was to replicate the experience of seeing objects and scenes in a way that appears more lifelike and immersive compared to traditional 2D TV.

Key points about 3D TV include:

1. Stereoscopy: 3D TV uses a technique called stereoscopy to present different images to the left and right eyes, simulating the way human vision perceives depth. This is achieved by either polarized glasses, active shutter glasses, or glasses-free autostereoscopic displays.
2. Glasses-Based 3D: Many early 3D TVs required viewers to wear special glasses that synchronize with the TV to deliver different images to each eye. Polarized glasses use different polarizations for each eye, while active shutter glasses rapidly alternate between blocking one eye and the other.
3. Glasses-Free 3D: Some 3D TV models aimed to provide a glasses-free experience using autostereoscopic technology. These displays use special lenticular lenses or parallax barriers to direct different images to each eye.
4. Content Availability: 3D TV required content specifically produced in 3D format. This included movies, TV shows, and sports events shot with specialized cameras or converted into 3D during post-production. However, the availability of 3D content was limited compared to traditional 2D content.
5. Popularity and Decline: 3D TV gained popularity for a brief period, with manufacturers promoting it as the next big thing in home entertainment. However, it faced challenges including the need for specialized glasses, viewer discomfort, and limited content. As a result, interest in 3D TV declined over time.
6. Consumer Feedback: While some viewers enjoyed the 3D experience, others found it uncomfortable, experienced eye strain, or simply preferred traditional 2D viewing.
7. Obsolete Technology: Due to various factors, including lack of consumer demand and technological advancements in other areas of TV technology, most manufacturers phased out 3D TV models by the mid-2010s.
8. Current Trends: Modern TV technology focuses on higher resolution (such as 4K and 8K), HDR (High Dynamic Range), wider color gamuts, and improved refresh rates, aiming to enhance overall image quality and viewing experiences.

While 3D TV was a notable experiment in enhancing home entertainment, it ultimately didn’t become a mainstream staple of television technology due to various limitations and challenges. As of my last knowledge update in September 2021, 3D TV has largely faded from the market, and manufacturers have shifted their focus to other advancements in display technology.