What is DVD?
DVD stands for Digital Versatile Video Disc or Digital Video Disc. It is an optical disc designed to store many different kinds of data. Many years of research and development had preceded its arrival as the "next generation" format of home entertainment. The movie industry saw it as the perfect medium to deliver higher quality movies
to consumers as compared to VHS. Mass marketing of DVD movies and DVD players 
began at the end of 1997. Well over 500 DVD movie titles were released, and the rate of new releases rapidly increasing from that point forward. Movies on DVD are capable of a picture with more than twice the detail of a standard VHS video tape.With better quality, ease of use, direct access to any part of the disc, and better durability and longevity, it’s not hard to see why weekly DVD movie rentals began to surpass weekly VHS movie rentals by mid 2003. DVD has widespread support from all major electronics companies, all major computer hardware companies, and all major movie and music studios. With this unprecedented support, DVD became the most successful consumer electronics product of all time in less than three years of its introduction. Wether it's movies, TV shows, or special interest videos, the DVD is still the dominant format of home video distribution world wide.
DVD Image and Audio Quality
Normal VHS tapes have a screen resolution of up to 240 lines of horizontal resolution. DVD video has up to 500 lines of horizontal resolution. And because DVD is an all-digital format, it offers superior sound clarity and picture resolution, which are more enjoyable displayed on regular TVs, but can be best appreciated while watching your favorite movie with a state-of-the-art home theater system
. DVD image Quality depends on many production factors as well as the encoding process. A poorly encoded DVD sometimes contains visible artifacts such as color banding, blurriness, blockiness, fuzzy dots, shimmering, missing detail, and even effects such as an image that "floats" behind the rest of the moving picture. In general however, DVD is vastly superior to consumer VHS videotape.DVD audio quality is also superb. DVD includes the option of PCM (pulse code modulation) digital audio with sampling sizes and rates higher than audio CD. Alternatively, audio for most movies is stored as discrete, multi-channel surround sound using Dolby Digital or DTS audio compression similar to the digital surround sound formats used in theaters. As with video, audio quality depends on how well the processing and encoding was done. In spite of compression, Dolby Digital and DTS can be close to or better than CD quality.
About the Disc
The DVD is the same size as a conventional compact disc but can hold a LOT more information (data and/or video). The DVD's storage capacity is seven times that of a CD, which is 4.7-gigabytes on a single-side/single-layer disc. A DVD video disc can hold up to 133 minutes of full motion video per side on a single layer disc. That means 95 percent of all movies to fit comfortably on a single-layer DVD, eliminating the need for flipping the disc over during movie
playback.This capacity is nearly doubled to 8.5 -gigabytes on a single-side/dual-layer DVD, which delivers over 4 hours of movie or video content on a dual layered disc. It provides plenty of extra room for multiple audio, language, and subtitle tracks; bonus materials; menu screens; and other features unique to DVD. There is even a double-side/dual-layer DVD, which quadruples the storage capability to 17-gigabytes. You can see that it is an amazingly flexible medium for data storage, high-definition computer games and multimedia applications.
DVD Aspect Ratio
You are usually given 2 choices to watch movies on a DVD. Full Frame, or Letterbox. This is due to the aspect ratio of movies which is different than a regular TV set. Aspect ratio is the ratio between the width and height of an image. 4:3 is the standard aspect ratio for a regular (standard definition) television. That means that it is 4 units wide by 3 units high. Movies are shot in an aspect ratio that is much wider than 4:3. To view movies on a regular TV you need to decide which version you want to see. Full Frame (also called pan & scan) will fill the frame (by excluding some of the original image). Letterbox (also called widescreen) will fit the whole movie image side to side and then fills in with black bars on the top and bottom.
When watching a movie on a high definition screen that has an aspect ratio of 16:9, choosing the widescreen version will completely fill the frame if the movie is shot in the HD aspect ratio. Movies shot in wider ratios will still have a small amount of black on the top and bottom of the screen. It is not uncommon that BOTH the widescreen version AND the Full Frame version are included on the same DVD disc.
What is Region Encoding?
Because DVD is subject to the same issues of piracy and market sharing that govern the entire video industry, region encoding was introduced to set geopolitical boundaries for compatibility of DVDs and players . There are 6 regions for DVD players & movies. As an example, a DVD encoded for Region 1 (U.S. and Canada) can only be played on a Region 1 DVD player. Make sure to get a player and buy or rent movies that are encoded for your area, although there are some discs that will operate in all regions. They are sometimes known as "All Region", "Region Free" or "Code Free". You can also purchase an all region DVD player .
