How does HDMI over CAT5 work?

So I have just learned about HDMI over CAT5, this sounds awesome. But I am having trouble finding information about it as google's result list is saturated with products and not info.

So how does this work? Does a CAT5 cable essentially do an inline replacement of a HDMI cable or does the setup run over an existing network?

I also see that there are some solutions that require two CAT5 cables and some that require one. What is the main difference? Can I get away with one and a gigabit network?

Are there HDMI switchers and if so how do they work? I want to move my cable box (which can be controlled over WIFI) and a computer into a different room, only one will need to be active at a time, but how would I change which signal source to show remotely?

And lastly, from my initial research there are tons of products. Is there anything to avoid when looking for something to buy? Any recommendations?

Is audio also supported? Is there any compression with the video or audio on any of these solutions?

Thanks! (I should also point out I do not know the terminology or all the options so if I am looking in the wrong direction please point me right! I just basically want to move my cable box and computer to another room, controlling them remotely is taken care of, the HDMI link is what I am missing.)

Solution 1:

HDMI over CAT-5 "Extenders" just use the Cat-5 network wiring to transmit their signal in place of an HDMI cable. If you put a switch (or alike) between the ends, it won't work. Example

There are DVI/HDMI-over-IP solutions out there as well, primarily for digital signage. Example