Many people are a bit hazy on networking terminology because until the last few years, most were happy enough with their ISP provided gateway or the consumer device they grabbed at Best Buy or Walmart. People just didn’t have enough devices & regular uses for it to really matter. Modem and Router are seemingly used interchangeably, and when I talk to some people ‘router’ means WiFi too. This is a quick and easy guide to networking equipment and their functions, so you can communicate clearly about your network related stuff from now on. Home networks are on the rise and getting more complex, so the better you can communicate, the easier your technology life will be.
A modem is the device responsible for moving data between your network and your ISP’s. Since Ethernet can’t run longer than 300ft, ISPs have different protocols and technologies to move data over distance. The modem translates these protocols back into something your network can use locally. DSL is a technology that does this over phone lines, while DOCSIS is the protocol for running internet over coaxial cable (Comcast, Cox, Century Link, etc). Thus a cable modem, while relatively inter-operable between cable providers can’t interface with AT&T DSL based networks. A DSL modem would be needed for that.
As an aside, If you are one of the lucky few who actually have true Fiber-To-The-Home service, you actually get normal Ethernet-style traffic over long distances (the whole point of fiber), with no protocol translation needed, thus the box your fiber comes to is not technically a modem even though it is roughly analogous to one as far as users are concerned. These are usually termed PON devices, for passive optical network.
Next up is the Router, which is by far the most misused term by most people, since all-in-one devices are common and usually branded and sold as “wireless routers”. In network terminology though, the function of the router is to control traffic inside a network, as well as interface this traffic with external connections. It is the brain of a network, basically. It decides what data is allowed to go where and in what manner.
That’s all the router does.
It doesn’t handle transmission to your ISP, it just sends a stream of data at the modem for the modem to handle, and interprets the data coming back from the modem. It doesn’t handle wireless traffic at all. People just think it does because they have only bought consumer routers with wireless chips soldered to the same board as the router and a 4 or 5 port switch. It’s literally a processor and memory doing the thinking for your network with an interface for outside your network (WAN), and an interface for inside your network (LAN). High end business routers often only have a pair of fiber ports and maybe a pair of Ethernet ports, on the assumption that a dedicated switch will be on the other end of the LAN connection.
A switch is hardware designed to connect devices to the router and other network devices. Most people can think of it like a powerstrip for internet, and be accurate enough to get by in daily life. Nicer switches handle more throughput and intelligently pre-route traffic to take some of the load off of the Router itself. It is the backbone of any local network in practice. If you transfer a file from one computer to another in your home, odds are the traffic is handled almost entirely by the switch. Your wireless router or ISP provided gateway have a 4 or 5 port switch soldered to them to connect a handful of wired devices, so people often conflate the two since nobody will refer to those ports as a separate switch.
Wireless Access Points
Wireless Access Points are wireless radio devices with embedded processors to handle interactions with wireless clients and move their traffic to the rest of the network, ideally over a dedicated Ethernet connection.
Wireless access points used to be totally alien to home users, but as the average american keeps adding more and more smart devices to their home, they too started to run into the same problem businesses had a decade ago, and we are now starting to see multiple access point products coming to home users, typically in a mesh configuration, though that is less than ideal because of how physics works. Wires will always be king, and WiFi is a limited resource no matter what you do. Only so many devices can talk to one radio at a time. That’s why in College lecture halls, airports, etc you will see multiple APs covering the same area. This is the only way to add more wireless capacity. Essentially add more teller windows at the Wifi device service queue. A typical home is far better served with 2-3 Wireless Access Points over the fanciest all-in-one router you can find.
ISP Provided Gateway
This device is All 4 of the devices we already explained rolled into one, sharing a processor and memory at a price point and configuration your ISP likes. They typically build a unit just well enough to avoid the majority of tech support calls. It’s actually literally the industry justification for spending more than $50 on a box, to lower costs on the backend support. Before they worked that out, they literally bought the cheapest thing that would technically work. Most people actually rent this from their ISP. So they pay for it mulitple times over, despite it being garbage for almost all users.