It seems that in the next few years (before OLED TV prices hopefully drop to a comparable level to LCDs), people wanting to buy a premium TV will have two options: 4K LCDs or FHD OLED TVs. 4K resolutions usually means 3840 × 2160 (although some offer different resolutions) - or about 4 times the pixels of FHD resolution, hence the 4K name.
Obviously this makes sense. The higher pixel density means smoother images. But does it really make sense? There are two main issues here: suitable content and whether you can actually tell the difference.