Wireless versus wired.  Wi-Fi is the wireless counterpart to Ethernet, which is the universal standard for local area networks (LANs).  In both homes and offices, networks are generally a mix of Wi-Fi and Ethernet.  Most stationary machines are cabled together via Ethernet, because there is an Ethernet port on every modern computer.  Wi-Fi networks (Wi-Fi hotspots) are set up for laptops, smartphones and tablets.  However, any desktop machine can be made wireless with an adapter (see 
wireless adapter).  See 
Wi-Fi vs. cellular, 
wireless router, 
access point, 
Ethernet, 
Wi-Fi and 
LAN.
Network Symbols
The Ethernet icon represents machines wired together, whereas the Wi-Fi symbol conveys transmission over the air.
NFC, Not Wi-Fi
Although somewhat similar to Wi-Fi, the contactless payment logo on credit cards identifies NFC transmission.  See 
NFC.