The term standard definition television (SDTV or SD) refers to a set of standards for television broadcasting and reproduction. These standards specify the size and frame rate at which video must be broadcast or reproduced to guarantee compatibility with television sets.
SD are based on three standards which were put into effect before the advent of digital television: PAL (formerly used in Western Europe excluding France and much of Asia, Africa and South America), SECAM (formerly used in France, Eastern Europe, the CIS and many West African countries), and NTSC (formerly used in North America and some Asian and South American countries).
Standard definition formats are nearly as old as television broadcasting itself, with their roots spanning back to the 1950s. By comparison to more recent standards like high definition (HD), SD standards use relatively low resolutions.
The majority of television broadcasters in Switzerland now use the high definition (HD) standard. Only a handful of channels are only available in SD. SD formats are the standard video formats used for DVD video.
Customers of Swiss cable TV service providers like UPC and Quickline should note that the basic TV plans offered by these providers only include the SD versions of many popular TV channels.
SD resolutions range between 544x576 pixels and 704x576 pixels for a total of either 313,344 or 414,720 pixels. That is a great deal lower than the 1280x720 (921,600) resolution delivered by HD.
More on this topic:
Swiss TV plan comparison
Deal of the Day 
