Equivalence of Network Name, SSID, and ESSID

ESSID and BSSID are just their IDs respectively.

If I am correct, ESS is the union of a set of BSS's.

iwconfig interface [essid X]

Why does it have an argument essid rather than bssid?

wpa_cli has a command bssid <network id> <BSSID> set preferred BSSID for an SSID

wpa_passphrase uses an argument for a SSID

SYNOPSIS wpa_passphrase [ ssid ] [ passphrase ]

wicd-wired-settings.conf has the following settings: bssid = <BSSID_of_network>

This value can be found using iwconfig(8).

essid = <ESSID_of_network>

This value can be found using iwconfig(8).

My understanding is that ESSID is the name of the access point, which can be changed.

On the other hand, BSSID is a numeric ID of the access point (something like the MAC address of the router).

You can list networks with their respective ESSID and BSSID with nmcli dev wifi

Or for cleaner output you can do nmcli -f SSID,BSSID dev wifi.

Also with iwlist, for example: sudo iwlist wlp2s0 scan

SSID: Network name (friendly, text, even with non-ISO basic Latin characters, up to 64 characters).

Could be hidden (no broadcast).

Sometimes "wrongly" called ESSID since it might group a set of APs under one name, but there is formally no such thing as an ESSID in the 802.11 standards.

BSSID: MAC address of the access point, it uniquely identifies each one.

All the APs' beacons will broadcast the same SSID but different BSSIDs.

Reference Understanding the Network Terms SSID, BSSID, and ESSID

What's the difference between a BSSID and an ESSID?

This is the so-called Service Set Identifier (SSID) of your network, which is also referred to as “Network Name.”

There’s formally no such thing as an “ESSID” in 802.11 standards. Thus, you can just use the same SSID for ESSID-shared networks.