An HDMI splitter typically distributes the HDMI signal from an HDMI source to 2 or 4 screens. There are also applications in which the HDMI signal is distributed to 2 different HDMI sinks, eg to a TV and an AV receiver for the sound.
Yes, an HDMI signal can be split or distributed. The splitter distributes audio and video signals from an HDMI source. Connected devices basically have the same signal.
A splitter distributes the signal, eg 1 player to 2 TVs. A switch, on the other hand, works in reverse and switches between different sources, eg 3 players on one TV. The combination of HDMI switch and splitter is called HDMI matrix switch, eg 4 players on 2 displays.
No, all connected monitors get the same picture. To extend ("Extended Desktop"), the computer must either have 2 graphics outputs or a special USB-C / DisplayPort connector that supports the function. It doesn't work with an HDMI connection.
No, the quality remains the same before and after a splitter. The transmission is fully digital. The AV formats should be considered if 2 very different HDMI sinks are connected. Should the signal be optimal for device 1 or for device 2? Or should both be able to handle it? These can be mutually exclusive. In order to find the right solution, almost all of our splitters have a so-called EDID management. So you can set it as you want.