I thought the Ethernet is logically a one-line communication bus (for argument's sake, I am excluding hubs). All machines attached on the bus hears the same signals and the machines themselves try to avoid collisions by randomly backing off.
If so, why would splitting one Ethernet line from my home router into two and connecting two computers not work? Why do I have to add a switch to it?
*What the Internet said would not work.
[4 port home router] ------[one Ethernet cable]-----[simple splitter]======[two computers]
*What the Internet said I should do
[4 port home router] ------[one Ethernet cable]-----[switch]======[two computers]
Is this because of the signal degradation (reduced electric current)?
Thank you for all the answers! The reason why I did not just use the two ports of my home router is...
The 4-port gigabit router is in my room, and I had put a computer in another room (also my room, though). Since a wired network is far more reliable and secure, I had bought a long Ethernet cable and and connected the computer to the router. Now I was thinking about adding another computer to that room. I could buy another long Ethernet cable, but then there will be two cables between the rooms. The one line already is a minor annoyance, so I thought if I could share the one line between the two computers in that room. A switch would work, but it requires power and is a little bit pricey. That is why I wondered why it would not work to simply split the physical Ethernet cable.
Apparently I do not completely understand how Ethernet and a switch work. I just have some bit of knowledge I heard in my college class.