IP address
The “street address” of a device on a network

Whenever packets cross a network, something has to say from where and to where. That is the job of the IP address.

What it is

An IP (Internet Protocol) address is a label assigned to a device’s network interface. Routers use it to forward traffic toward the right place, much like a postal address (though addresses can change; details depend on your setup).

Global vs private

Two broad families show up in homes and offices:

• Public (global) address: What the wider internet “sees” for your connection at the edge—often shared or rotated by your provider.
• Private (local) address: Used inside a LAN (Wi−Fi, office VLANs) to tell devices apart. Your laptop and your TV each get one, managed by a router.

Think: one building number (public) and many room numbers (private) behind the same front door—not a perfect match, but a helpful mental model.

IPv4 and IPv6

IPv4 uses 32−bit style addresses—only about four billion unique values, not enough for today’s ocean of devices. IPv6 is a newer, vastly larger space so we can hand out more addresses and simplify some routing design in the long run.