On new TVs, what does 1080p, or 810i mean?

The numbers indicate the number of horizontal lines that the set can display. The letter (i or p) indicates how the image is drawn on the screen -- 'i' stands for Interleaved and 'p' stands for progressive scan. A little history will help you understand more clearly.

The old style Standard Definition TV, or NTSC, the mainstay of US television signals since the late 1940s had a horizontal resolution of 525 lines. Of those 525 lines, about 480 were actually displayed on the screen. Due to technological limitations of the 1940s, it was not possible for TV screens to display all 525 lines sequentially on a single pass of the electron beam. The first pass of the electron beam drew every other line and the second pass drew the missing lines from the firs pass. This happens fast enough (60 times per second) that the human eye doesn't notice the effect; our brain reassembles the image into a single coherent image at a net rate of 30 frames per second. This is fast enough to avoid any "flicker" in the image. This scanning method is known as Interleaved Scanning. Since the old NTSC image displayed about 480 lines (it's actually a few more than that) it is sometimes referred to 480i.

In the late 1980s and early 1990s, with the advent of DVD technology and improved CRT technology it became possible to include more information in the alloted 525 lines. You may have noticed DVD players and TVs marketed as "Progressive Scan" models. This simply meant that it was now possible to redraw a complete 525 line screen in a single pass of the electron beam. When the technology first became available, the improvement was pretty stunning compared to the old Interleaved Scan method. Since the entire screen was redrawn in a single progressive pass of the electron beam it logically became known as "Progressive Scan." On an old TV it would be referred to as "480p."

Enter High Definition TV or HDTV. The two popular capabilities are 720 lines and 1080 lines. Obviously the more lines in the signal and the display the sharper the image will be. Images can still be transmitted and displayed as interleaved or progressively scanned images. The capabilities of the set you are considering are usually displayed prominently -- either 720p or 1080p -- although some lower priced sets don't specifically say; you should presume those to be 720p at best.

Local broadcasters, especially in smaller markets, will probably continue to record and broadcast local programming in SDTV quality since the cost of converting to true HDTV is very high. Their actual broadcast signals will be full HDTV so network feeds will be broadcast at whatever definition that the network provides. In those markets you probably won't notice any difference for quite some time with HDTV if you primarily watch local programming.

So, what should YOU buy? Well, that can be hard to say exactly. A high quality 720p set can be nearly as good as a mediocre 1080p set. And for an old fart such as myself with terrible eyesight, I can't tell any difference between the best of the 720p and 1080p sets. They're both a massive improvement over the old 480i of SDTV but for the life of me I can't tell any difference between the best of the 720p and 1080p sets. The best way to decide is to compare sets side-by-side and make your decision based upon what your eyes tell you. Just make sure that the seller is using true 1080p signals or there won't be any difference between the sets on display no matter how good they are.

One thing to watch out for are sets branded as "1080i." That's just a glorified 720p set and in my opinion is dishonest advertising. On that basis alone, I'd give those sets a pass.

The Numbers refer the the resolution of the picture. Larger Number, better Quality/ the number of pixels on the screen. The i and the P represent how the signal is sent to the Tv. In the long run it really wont make a difference, they both will look exactly the same.

Go for the 1080 if you are going above a 32" tv, but stay at 720 if your 32" or below, the quality will look too clear. Meaning when you watch a movie with a lot of special effects, it looks choppy and fake.