We've been having some trouble with our wifi lately. If anyone out there is knowledgeable about the details of ethernet networking, could you explain whether we need a router or a switch? We only use one of the two computers at a time, so dividing up the bandwidth won't be a problem. I think a switch would be sufficient, but I do want to make sure. Are there any terms to watch for in picking one?
@Rosemary A home router typically accepts a connection from a WAN (Wide Area Network, typically a cable or DSL modem) and provides NAT (Network Address Translation) so more than one device can share a single IP address. Most home router today are also wifi access points. Any router that has more than one LAN (Local Area Network, home Ethernet) port also has a switch built-in, usually without saying.
contd
@Rosemary An Ethernet switch just allows multiple devices to connect to each other, mostly useful if your router was in one room, but you could only run one cable to another room with multiple wired devices. If you're only using wifi, you don't need a switch.
A wifi access point plugs into a router that doesn't have its own wifi (or its wifi is broken, etc) and acts as a wifi-to-wired bridge.
A wifi repeater connects to a wifi signal farther away and repeats it for greater range.
@Mycroft What we have is a single ethernet port to our apartment that goes back to a router somewhere else in the apartment complex. The switch should be sufficient for our needs. As I understand it, it just rebroadcasts everything to all of its ports?
@Rosemary If you do not control that router, or do not fully trust everything else plugged into that router (presumably other tenants' devices) I would recommend your own home router you control. That way you can control your own wifi access point too.
If you only use wired devices, and you trust the apartment's router, then just a switch would work fine. Assuming it provides internal IP addresses (typically with 192.168.x.x)
Noma 
@Nomaxice @Rosemary I'm afraid it's been a long time since I went shopping for one. I have a Ubiquiti EdgeRouterX myself, which is about us$50, but has no wifi and isn't the easiest to configure.
Most of the difference in router pricing has to do with wifi; if you don't stream 30 4k videos half a mile away there's absolutely no need for the expensive ones.
@Nomaxice @Rosemary https://m.newegg.com/products/9SIA25V80J2459 shows a basic one new for under $30, if you search 'gigabit router' there's also a few refurbished ones in the 15-20 range
sort by price lowest, and just ignore all the things that are obviously not gigabit routers
@Nomaxice @Rosemary whoops good catch, that is indeed just a switch, here's a new router https://m.newegg.com/products/9SIACYN5X10138 $37
refurb one for $18 https://m.newegg.com/products/9SIA52E8244812
@Rosemary Home routers are very very easy to set up to get them working. Most can just be plugged in and step you through basic configuration on screen, with built in documentation in the web interface. Maybe a single fold-out page of instructions is included to double check which gets plugged in where.
@Rosemary There shouldn't be any "allowed to" - it's basic networking. Only reason they wouldn't want you to is tech support - if something goes wrong with your equipment, it's extra steps for them to troubleshoot and isolate the problem.
@Mycroft We would also have to get someone to explain to us how to set up a router, because we've never done it before. Is it complicated?