For television buyers, there’s only one letter that will truly matter in the future and that’s the letter K.
Consumers who have shopped for TVs lately have undoubtedly been asked what version of high definition they’re after. The vast majority of televisions today come with a 1080p resolution. Recently, however, an increasing number of televisions have hit store shelves that deliver 4K resolution. The K in that equation may mystify some consumers. After all, it’s a relatively new entrant and without context it means nothing.
In general, a number followed by the K defines the number of horizontal lines that run across the screen to create a picture. In theory, a 1080p television could be considered 2K, since it has nearly 2,000 horizontal lines (1,920, to be exact). A 4K TV, with its 4,096 horizontal lines, therefore, delivers more than twice the resolution. To make matters worse, there are other Ks to worry about.
Apple’s (AAPL) 27-inch iMac, for example, has offered 5K resolution with 5,120 horizontal lines, since last year. (Last week, the company announced its entire 27-inch iMac line would offer 5K resolution.) Meanwhile, 8K is starting to surface as an emerging technology that could, well into the future, become the new standard.
“For TVs, the next evolution is 4K because we are still at the early part of the adoption curve,” says IDC analyst Linn Huang. “I suppose if we are thinking about a very long-term view, I would assume that 8K would be the next destination. 5K is largely locked to one panel size at the moment (27 inches), meaning this resolution will largely remain a monitor/all-in-one desktop PC specification. Some TV vendors are already working on 8K TVs, but these aren’t really ready for the market and the market is not really ready for these TVs.”
In theory, the more lines used to create a picture, the more detail and, thus, the better the picture. Therefore, some may believe that buying a 4K television rather than a traditional full HD, 1080p television, may be preferable. In reality, there are several roadblocks that will ultimately ratchet back the 4K craze.
One of the major roadblocks to 4K TVs, and one of the main reasons some may hold off on buying new televisions with the technology, is the general lack of content. As Huang notes, the vast majority of broadcast television content Americans watch today is delivered in standard HD resolution of 1,280-by-720 and not full HD. A precious few companies are even considering delivering 4K content to movies or TVs in the near future, and devices like Apple’s iPhone have only just begun to capture 4K video. While the buildup of 4K content is growing, it’s happening at a snail’s pace.
“Netflix has select content available in 4K and is reportedly shooting some of its original content in native 4K,” Huang says. “Comcast announced that it will release their first 4K set top box this year… however, 4K TVs will remain a very small part of the TV installed base worldwide even in five years.”
What’s more, the true value of 4K may only be experienced on larger screens. In smaller displays, packing in more lines does not necessarily deliver the same visual-quality improvements that one could find in a larger screen.
According to IHS analyst Paul Gray, television vendors can deliver the best visual quality in screens of 50 inches and above. Gray says that by 2018, “all sets of 50 inches or larger will be 4K.” The “entry size” for an eventual 8K television will be 65 inches, but the “real experience” of enjoying the higher resolution won’t result until consumers watch content on 80-inch televisions.
Despite those caveats, 4K televisions, which are currently substantially more expensive than their 2K alternatives, are expected to grow in numbers. Brian Markwalter, senior vice president of research and standards at the Consumer Electronics Association (CEA), says 4.5 million 4K sets will be sold in 2015. That figure will jump to nearly 9 million next year. “4K Ultra HD will make up almost 50% of TVs over 40 inches sold in 2016,” Markwalter says.
In April, research firm IHS said that the global demand for 4K content is on the rise. The company noted that the 4K-display market—which includes televisions, as well as smartphones, PC monitors, and other components—will hit $52 billion by 2020. That’s up from $9.2 billion last year.
Still, it’s hard to tell whether that increase in demand will be the result of vendors foisting upon consumers 4K technology or whether the technology is truly desirable. Markwalter pointed to research conducted by CEA earlier this year that shows consumers care most about picture quality when buying a new television. While 4K technology certainly plays into that, Gray argues that resolution alone is not sufficient to deliver the best picture quality.
“For premium coverage like major sports events [4K] gives an enhanced sense of realism,” Gray says. “However, there is far more to perception than simply resolution: color accuracy, sharpness of moving objects and dynamic range are more important.”
Indeed, the goal is ultimately not more pixels, which higher K devices will offer, but something much different.
Sign up for Data Sheet, Fortune’s daily newsletter about the business of technology.
For more on high-end TVs, check out the following Fortune video:
