The highest display resolution of the 58XT880 is 4K Ultra HD. That's over four times the display resolution of a Full HD TV, which is the most common display resolution. 4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
A 4K Ultra HD HD type is actually the best display resolution amongst all TVs of a comparable type and age to the 58XT880.
A Full HD HD type is the worst display resolution amongst comparable types of television.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
Other 4K Ultra HD televisions currently available which you might also want to look at include because of it's better review score, the UE65HU7200 (£1,499.00), or the UE65HU8200 (£2,079.00) both from Samsung or the Sony KD-65S9005 (£1,899.00).