4K Ultra HD

What is 4K Ultra HD?
4K means four times sharper than HD
8,294,400 is a random number until you see it means there’s four times as much detail in the resolution of the picture. 8,294,400 more pixels of resolution, to be exact. This amounts to a crisper image, smoother lines, and richer detail.

High dynamic range (HDR)
Darker and brighter than ever before
HDR adjusts the dark to show darker and the bright to shine brighter. Every image jumps off the screen with the darkest dark contrasted against the brightest bright.

1. What do I need to watch 4K Ultra HD content?

To watch content from Prime Video you’ll need a 4K Ultra High Definition (UHD) display and a device that supports the 4K UHD format. This includes 4K compatible Smart TVs and streaming media players (like Amazon Fire TV and Fire TV Stick). You can also view 4K UHD content playing 4K UHD Blu-ray Discs. Whichever way you go, disc or streaming, you’ll need the latest HDMI cable to ensure you get features such as HDR.
2. If I buy an Ultra HD Blu-ray player will it play my current discs?

Yes. Ultra HD Blu-ray players will play your 4K UHD Discs as well as your Blu-ray Discs and even your DVD’s.
3. Can I watch 4K discs on my Blu-ray player or regular DVD player?

Ultra HD Blu-ray Discs cannot be played in a standard Blu-ray Disc player or DVD player.
4. Can I stream a digital 4K Ultra HD title on a non-4K device?

Yes, the video will switch to a format your device can support (e.g. HD instead of UHD or SD instead of HD).
5. How do I find 4K Ultra HD and HDR movies and TV shows to watch?

On Prime Video you can find movies and TV shows either on our 4K Ultra HD web page, or on your 4K enabled device by looking for rows labeled “4K Ultra HD” or “4K HDR”. To find 4K Ultra HD Blu-rays or DVDs, visit the Movies and TV category 4K Ultra HD store.
6. What is an HDMI cable and do I need one for my 4K TV?

For 4K Ultra HD sources like an Ultra HD Blu-ray player or a 4K streaming set-top box, purchasing an HDMI cable that’s rated to handle 4K bandwidth will provide the highest-quality picture and sound. The packaging, the cable itself, or the product description will typically tell you if the HDMI cable is fast enough for 4K. Look for HDMI cables labeled “Premium HDMI Cables” as these are optimized for Ultra HD performance.

More Infos here: 4K Ultra HD