Full HD camcorders are capable of showing high definition images that are up to five times as sharp and detailed as old style 'standard definition' images. When you see a camcorder which is '1080p' (like the Panasonic SD900) it is able to record in full HD and offers the highest possible levels of detail for your recordings.
So what can you do with the footage in HD? You can play back 1080p video on your computer, or your HD television. You might also want to create your own blu-ray discs (as long as you have a blu-ray player to watch them on). If you're in the market for a camcorder, make sure it is 1080p. There's some good info on all things 1080p over at Wikipedia. And there's a very helpful section at About.com on HD camcorders.
The Panasonic SD900 features a 12x optical zoom. Optical zoom lets you press a button on your camcorder and enlarge your subject. Zooming in lets you get closer to your subject without having to move closer to them. A handy feature you'll find in all camcorders. Optical zoom uses the camcorder's lens to enlarge the view, and won't distort the image the same way that digital zoom does. A camcorder with a 10x digital zoom will bring the subject ten times closer than it appears to the naked eye.
More information on Optical Zoom
Photoxels.com - Optical vs. Digital Zoom
The SD900 offers an HDMI output. HDMI stands for High-Definition Multimedia Interface and is a standard used for audio / visual equipment. Like the older scart, HDMI is a port that allows you to connect things like Blu-ray players and games consoles to your television. Unlike scart, they're very easy to plug in - and take up a fraction of the space scart leads do. HDMI allows for HD devices to send high resolution information to the television. HDMI is an uncompressed digital signal, as opposed to previous analog interfaces such as S-Video, component video and composite video. In short, HDMI is the best way to connect your AV equipment and is going to be with us a good way into the future. There's a really good blog post over at Hi-Def hardware if you'd like to find out more.
