This subject is a little deeper than I usually get.
I had a wired Linksys router for my home network for a number of years. It was fine for my three computers. When my grandson moved his computer upstairs I decided to get a wireless router to replace my wired router. This would allow me to set him up without running wires to his room. Having the wireless router downstairs provided to weak a signal for him to use his computer (at least for online gaming). I found out that I could use the wireless router as a wireless access point (kind of a wireless switch). It even had an IP address that was one removed from the wired router. This worked great. It was a G type router (max 54 Mbps) and it was still a little laggy for gaming so I ended up running a wire anyway.
Most recently I got another wireless router (an N type) which is theoretically twice as fast. I read the directions which told me to turn off DHCP on one of the routers (Domain Host Control Protocol if you’re interested). I immediately had trouble because unlike the wireless access point that I disconnected, the IP address on the new router was the same as the old router. (192.168.1.1) this meant that I had data collisions on my line because both routers were talking on the same address. It also made it impossible to talk to both routers from my computer. I found this one website (http://www.dslreports.com/faq/6742) that told me to set the IP address of my router to something way out of range of the router that was supplying DHCP. I did this, and then I couldn’t access the new routers settings at all. . This was because the new address was completely removed from my subnet that the original router supplied. Since I had moved the second routers address well out of the range of the first router, I could have turned DHCP on the second router back on. This would have meant that I had two separate subnets talking to the internet. The drawback in this is that computers on the first subnet can’t talk to computers on the second subnet and vice versa. I finally just used the new router as my main router and reconnected the wireless access point for the added wired connections I needed. Now I can access my network wirelessly through two wireless devices, an N type and a G type. What I could have done was move the IP address of the old router to 192.168.1.2 so it was in the same subnet as the new router and then I could have talked to both the wired router and the new wireless router. The subnet mask 255.255.255.0 is what determines what addresses you can talk to on your home network. The zero at the end gives you an address range of 1 to 253 (254 and 255 are not usable by your computer). This has been very educational to me. Here is another source of information.
None of this even scratches the surface of networking.