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The appearance of LG's 15-inch OLED TV at IFA 2009 is a small (but significant) step on the road to replacing LCD, LED and plasma technology.

It's still early days, but thinner, crisper, brighter and more energy efficient TV screens are closer than you think.

Not sure what OLED is? Wondering why you'd want an OLED TV when all the chatter at IFA is about LED and 3D TV? Here's OLED explained...

1. What is OLED?

Pioneered by Kodak back in the 1980s, Organic Light Emitting Diode (OLED) technology is poised to oust LCD just as LCD stuck the knife into the CRT.

An OLED panel consists of a layer of organic, light-emitting material sandwiched between two conductors (an anode and a cathode). This diode layer emits light when an electric current is passed through it. A TV panel features thousands of OLED pixels mounted in rows and columns onto a TFT array. This is referred to as an Active Matrix OLED or AMOLED display.

2. No backlighting required

Because the organic material used in an OLED panel emits its own light when charged, there's no need for a separate backlight. In comparison, LG's newly announced LH9000 LED TV relies on backlighting technology that "uses hundreds of LED elements to individually brighten and dim the image on the screen."

3. OLED outperforms LCD and LED

OLED TVs have several advantages over traditional LCD televisions. For starters, the lack of a backlight means that OLED TVs can be extraordinarily thin – the Sony XEL-1, for example, is only 3mm thick; Sony's prototype 21-inch OLED TV is a mere 1.4mm.

OLED pixels can also be turned on and off much quicker, giving OLED TVs a faster refresh rate, greatly improved contrast and unparalleled brightness. OLED panels are also far more energy efficient.

4. Sony, LG and Samsung love OLED

Some of the biggest consumer electronics manufacturers have jumped onto the OLED bandwagon. The Sony XEL-1 was the first OLED TV to become commercially available and Sony had a 27-inch prototype at this year's CES.

LG has quietly unveiled its own 15-inch model (reportedly available in December), while Samsung has also shown some love for the technology – it has already demoed a 31-inch model and a 40-inch screen.

5. OLED is available now (albeit in small sizes)

While the XEL-1 is currently the only OLED TV available, OLED technology is already being used in mobile phones, media players and digital cameras.

You'll find an AMOLED display in the Samsung Jet, the new Sony Ericsson Xperia X2 and X-Series Walkman, the Sansa Clip+, Nikon Coolpix S70, the OQO Model 2+ and forthcoming Zune HD. There's even an OLED keyboard – the OCZ Sabre OLED Keyboard has 9 programmable OLED keys.

6. OLED is expensive

Consider this: instead of plunking down £2,500 for an 11-inch Sony XEL-1, you could buy a 42-inch Philips 42PFL9664 or a classy Pioneer PDP-5090 and still have change for accessories.

Manufacturing costs are the main reason why we're only seeing commercial OLED displays in small sizes. Is this why Sony is delaying its own OLED launches?

The worry for OLED is that the delay in producing decent-sized TVs gives LED technology more time to bed into the public consciousness. Worse still, the current buzz around Full HD 3D TV could also dilute OLED's advantages.

7. OLED can be 'flexible'

Dubbed FOLED (Flexible OLED), Sony and Samsung both demoed a bendy version of the technology in 2008. FOLED displays could be wrapped around pillars in shopping malls or used to add bigger, roll-up screens to mobile phones. Kodak has also shown off a flexible OLED prototype, with the added advantage that it can be used underwater.

Sony's 2.5-inch flexible oled display

8. OLED can be 'transparent'

Yes, there's also an acronym for this – TOLED. Boffins have envisaged that transparent OLED panels could be used to add TV screens to windows, as HUDs in future cars and to create stylish, sci-fi displays that look like sheets of glass.

There are also military applications to consider. Defence Update suggests lightweight PDAs and wearable "display sleeves". Other applications, they say, could include "automotive instrument panels, windshield displays and visor mounted displays".

9. There are other types of OLED

There are other variations of OLED technology. AMOLED (Active Matrix OLED) is the most commonly used OLED technology in high resolution panels. PMOLED (Passive Matrix OLED) offers a lower resolution and is better suited to displaying text and icons.

The glow provided by PhOLED (Phosphorescent OLED) device could provide an eco-friendly alternative to traditional lighting. While SOLED (Stacked OLED) uses a revolutionary new pixel layout that literally 'stacks' the red, green, and blue subpixels on top of one another. The result? Even better colour depth.

10. The disadvantages of OLED

OLED is viewed as the natural successor to LCD, but that's not to say it's a perfect technology. OLED displays are expensive to manufacture, especially in large sizes. Decent-sized OLED TVs aren't expected to be on sale until late 2010 or 2011.

There are also concerns about the lifespan of OLED displays. This perceived lack of reliability combined with sky-high price tags could mean that we might not see an affordable OLED TV before 2015. But we'd love to be proved wrong.