Splitters are in many ways, the direct opposite of a switch. A splitter connects one source device to many destinations. They can be used in a commercial environment, such as a retailer that sells multiple televisions. These televisions may all be displaying the same content simultaneously. Similarly, a club or pub showing a sporting event may want to show the big game on every TV at once. These situations need a Splitter.
You can use a Splitter in a home to send the same data simultaneously to a television and a projector so that the signal is ready regardless of which display device is needed at the time. You can also use a Splitter to duplicate the output from a computer to both a local monitor and a TV in another room.
With audio, a simple 3.5mm splitter cable may be all that you need. Passive splitters can also be used for VGA, RCA and Antenna cables. Generally, analog signals stand up better to passive splitting than digital, but there are limits. Passive splitting halves the available power each time, which can greatly affect volume, picture quality and cable length.
Passives splitters can also be used for digital signals like HDMI and Optical audio, but these are generally more sensitive, which can cause some hiccups under adverse conditions.
Splitters can also be active. Powered splitters take power from a mains outlet and have the benefit of boosting the signals on every output to ensure they are at full strength. This gives them the ability to run more destinations at once over longer cables.