What is an IP address?¶
title: "What is an IP address?" card_id: "IP-007" status: "complete" source_document: "https://docs.google.com/document/d/1BAAmgJp42irDazpTlr26cb2DndLbgoRSwbVhXpD3Otw/edit?usp=drivesdk"
What is an IP address?¶
Right, let’s do IP addresses properly.
People use the term all the time.
And quite often, they use it as if an IP address is some sort of unique tracking number attached to a person or a device.
It isn’t.
So, what actually is an IP address?
IP stands for Internet Protocol.
Now, protocol is one of those technical words that can make something fairly simple sound much more complicated than it really is.
A protocol is basically an agreed set of rules.
In this case, it’s part of the set of rules that allows information to move across networks.
Let’s say you want to open a webpage.
Or send a message.
Or upload a photograph.
Whatever you’re sending has to be turned into data and moved from one place to another.
That data will normally be broken into smaller chunks called packets.
The easiest way to picture one of those packets is to think about an envelope.
Inside the envelope is the thing you actually want to send.
That might be part of your message, photograph, webpage or login request.
That’s the payload.
On the outside of the envelope is information that helps the network work out where it’s going and where it’s come from.
That’s where IP addressing comes in.
An IP packet normally contains a source IP address and a destination IP address.
The destination address helps the network work out where to send the packet.
The source address shows where that packet appears to have come from at that point in the journey.
As the packet moves across the network, it passes through equipment called routers.
Those routers don’t need to understand your photograph, read your message or know why you’re logging in.
They look at the addressing information and make a decision about where to send the packet next.
It’s a bit like a series of sorting offices moving an envelope towards its destination.
So, at its most basic, an IP address is addressing information.
It helps data get from one point on a network to another.
That’s the core idea.
It isn’t a person’s name.
It isn’t automatically a device identity.
And it isn’t a permanent digital fingerprint.
That distinction matters because people often talk about an IP address as if it belongs permanently to one device or one individual.
But that isn’t how networks normally work.
One device may use different IP addresses at different times.
Your phone might use one address on your home Wi-Fi and another when it moves onto its mobile connection.
If you connect through a VPN, the online service may record an address belonging to the VPN rather than the address normally used by your home or mobile connection.
The address assigned to you by an internet provider may also change over time.
And several devices—or sometimes several different customers—may appear to use the same public IP address.
There are several different reasons why that can happen.
For now, the important point is that an IP address describes something about a network connection.
It doesn’t automatically tell you who was sitting behind the device.
You’ll also see IP addresses written in two main forms.
An IPv4 address is usually written as four numbers separated by dots.
Something like:
192.168.1.10.
An IPv6 address is longer. It normally contains numbers and letters separated by colons.
They look very different, but they’re doing the same basic job.
They’re providing addressing information so traffic can move across a network.
There are also public and private IP addresses.
A public IP address is used on the wider internet.
A private IP address is used inside a local network, such as a home, office, school or hotel.
That difference becomes important when you’re trying to understand where an address appeared and what it might represent.
Public and private addressing is a subject in its own right, so we’ll deal with that separately.
So why does any of this matter when you see an IP address recorded by a system or service?
Because the system will normally record the IP address it saw at that point.
That might be the public address of a home broadband connection.
It might be part of a mobile provider’s shared infrastructure.
It might represent a workplace network, a hotel, a cloud server, a VPN or something else entirely.
The IP address can help you understand which connection, network or service was involved.
When it’s combined with accurate timing and other information, it may also help connect activity across different systems or events.
But the IP address doesn’t do all of that by itself.
So, if you remember nothing else from this explanation, remember this:
An IP address is part of the addressing information used to move data across a network.
It tells you something about where network traffic was going and where it appeared to come from.
It doesn’t, on its own, tell you who was responsible.
You don’t need to memorise address formats, convert binary numbers or understand every part of networking.
The important thing is to stop thinking of an IP address as a person’s digital name.
It’s an address used by a network.
That can be extremely useful.
But it’s only useful if you understand what it is—and what it isn’t.