Layer 1 — Physical
Cables, signals, encoding, and the raw electrical or optical pulses that carry every bit across the wire.
Copper Cabling — Ethernet over Twisted Pair
COPPERThe physical medium that carries most wired Ethernet traffic — what twisted pair cable actually is, how it works, and how the categories differ.
Fiber Optic Cabling — Light as the Medium
FIBERHow fiber optic cables carry data as light, the difference between single-mode and multimode, and the transceiver modules that sit between glass and electronics.
Wireless — 802.11 and the Radio Layer
WIRELESSHow Wi-Fi transmits data over radio waves, what the frequency bands mean, how the 802.11 standards have evolved, and why channel planning matters.
Coaxial Cable — From Ethernet's Origins to ISP Last-Mile
COAXIALThe cable that built the first Ethernet networks, why it lost to twisted pair, and why it still carries millions of broadband connections today.
Signaling & Encoding — Turning Bits into Signals
ENCODINGHow binary data is converted into electrical or optical signals on the wire, why raw binary is not transmitted directly, and how encoding schemes evolved from NRZ through PAM4.
Ethernet Standards — From 10 Mbps to 400 Gbps
ETHERNET-STANDARDSThe complete evolution of Ethernet speed standards, what the naming convention means, and how each generation changed the cabling and signaling requirements.
Cables & Connectors — The Physical Interface Reference
CONNECTORSEvery connector and cable type you will encounter in a real network — RJ-45, LC, SC, SFP modules, DAC and AOC cables — and when to use each.