A TV's ability to produce deep, dark blacks is extremely important to picture quality. OLED TVs, like Sony's BRAVIA XR-65A80K, absolutely excel at this. Each pixel can turn on and off individually to display absolute black. This creates a contrast ratio that is essentially infinite, resulting in rich colors and an incredibly lifelike image.
This will be especially striking on High Dynamic Range content. The 'A80K supports the HDR10 format, which is mandatory for streamed 4K material and 4K Blu-ray movies. It also handles the more sophisticated Dolby Vision® format, which adjusts brightness and color levels in response to the video signal on a scene-by-scene basis.