01
Split it up
Your message is divided into chunks of data. Each chunk travels inside a packet with information about where it came from and where it is going.
A field guide to the internet
IP addresses
and packet types,
explained.
Every photo, message and video travels as packets. Learn how they find their way, one small piece at a time.
No experience needed / About 8 minutes / Plenty of pictures
A message takes a little trip
Addresses point the wayRouters choose the next hopPackets carry a piece of the messageSmall pieces. One connected world.
01 / Start with the big idea
Think of a message as a box of puzzle pieces.
When your device sends something, the network does not move one giant file in a single trip. It sends manageable chunks with directions attached.
02
Find the route
Routers read the destination IP address and pass each packet to the next network on the route. Different packets can take different paths.
03
Put it back together
Your device receives the packets and the right app makes sense of them. With TCP, missing pieces can be sent again and put in order.
02 / IP addresses
What is an IP address?
An IP address is a network address used to identify a source or destination. Routers use the destination address to move packets toward the right network.
Think of it like a postal address for a delivery. It gets the packet to a device's network, while other details help deliver it to the right app.
IPv4 and IPv6 are both in use. IPv4 is shorter and familiar. IPv6 was created with a much larger address space.
192.168.1.42
IPv4 · 32 bits · four numbers
A common private address. Each number is one byte, written from 0 to 255.
1928 bits
1688 bits
18 bits
428 bits
Example addressOften used inside a home network
Private address
Used inside a local network; not routed across the public internet. Your router often shares one public IPv4 address for the household.
Public address
Globally unique at a given time and usable for internet routing. A server's public address lets networks find it.
Try a subnet · 192.168.1.42/24IPv4
Network address192.168.1.0
Addresses in this block256 total
Address range192.168.1.1 – 192.168.1.254
What /24 means24 bits identify the network
03 / Inside a packet
What’s inside a network packet?
Tap a section of the packet to see what that layer does. The details differ a little between IPv4 and IPv6, but the big idea is the same.
A packet usually combines network directions, a transport protocol, and some data. On its local journey, it also rides inside a link-layer frame (such as Ethernet or Wi-Fi).
PACKET CONTENT ▧ part of a page, a message, a sound, or something else
↳The IP header carries source and destination addresses. Routers inspect the destination to choose where the packet goes next.
Keep in mind
The local link frame changes at each network hop. The IP addresses usually stay the same end to end, although tools such as NAT can rewrite them.
04 / Packet types
Packet types answer two questions.
People use “packet type” loosely. It might mean who should receive it, or which protocol is carried inside it. Here are both meanings.
Who gets the packet?
Destination styleChoose a delivery pattern to see how an address can be used.
One sender to one destination. This is the everyday pattern when your browser talks to a website.
Think: one-to-one conversation
What carries the data?
IP payload protocolThe IP header identifies what comes next. These are three familiar protocols.
A reliable, ordered byte stream between apps. TCP tracks what arrived and can retransmit missing data.
Think: careful delivery with a receipt
One useful distinction: unicast and multicast describe where packets go. TCP, UDP and ICMP describe protocols carried by IP. They answer different questions.
05 / Follow one packet
Follow an IP packet, hop by hop.
Imagine you open a website. Your device wraps the request in packets, your router sends them onward, and a web server sends packets back. Each router forwards the packet toward its destination.
Every IP packet has a hop limit (called TTL in IPv4). It decreases as routers forward the packet, so a packet cannot circle forever.
PACKET STATUS Ready at your device
Your device
Home router
Internet
Web server
Packet snapshotHOP 0 / 3
Source IP192.168.1.42
Destination IP203.0.113.80
IPv4 TTL64
Illustrative addresses only.
203.0.113.0/24 is reserved for examples and documentation.06 / Quick glossary
Networking terms, in plain English.
A few terms you’ll see again as you explore networking.
Router
A device that forwards packets between networks, using destination addresses to pick a next hop.
Subnet
A smaller network carved out of a larger IP address range. The prefix length tells you its size.
Port
A number that helps a device deliver network traffic to the right app or service.
Protocol
A shared set of rules for how devices format, send, receive, or interpret data.
DNS
The naming system that helps translate a name like example.com into an IP address.
TTL / hop limit
A countdown in each IP packet that helps stop it from travelling around a loop forever.
MAC address
A link-layer address used to deliver a frame across a local network segment.
NAT
A technique that rewrites addresses, often letting several private IPv4 devices share one public address.
Want the original specs?
This guide keeps it simple. These standards documents define the underlying protocols and address conventions.