What is an IP Address? - Definition & Explanation

Instructor: Lyna Griffin

Lyna has tutored undergraduate Information Management Systems and Database Development. She has a Bachelor's degree in Electrical Engineering and a Masters degree in Information Technology.

In this lesson, we will learn the basics of IP addresses, how and why they are used, and their role in the world of the internet. We will understand binary and decimal notations and the role of subnets in identifying networks.

What is an IP Address?

IP stands for Internet Protocol, which is a set of standard predefined rules used to govern the way data packets are sent over the internet. For two devices to communicate, they must be able to find each other. For two devices to find each other, their locations must be known to each other. These locations are identified in the computer world as IP addresses. An IP address, which is usually just called an IP, is a series of numbers used to uniquely identify a computer/device on a network or on the internet. The IP address basically indicates the location of a device on a network: it is a unique identifier for devices. This is similar to an address uniquely identifying a house. Every house is identified by a street number (IP address) that can be located on a certain street (network address). As such, two computers cannot have the same IP address on a network.

The addresses facilitate the devices' transmission of messages back and forth to each other. If you want to send an email, stream a video online, or receive a document, your device must have an IP address. Without this, the device cannot effectively communicate with or be located by other devices on the internet.

IP Address Notations

IP addresses are notated by a series of 4 sets of numbers separated by periods. Typically, IP addresses are made up of 32 binary bits (1s and 0s that the computer uses to communicate). These 32 bits partly identify the host (street number) and partly identify the network (street name). The 32 bits are divided into octets (8-bit numbers) separated by a period.

In a binary octet, each number consists of 8 digits comprising 1s and/or 0s.

Therefore, one octet of the IP address can only have a value that falls between 00000000 and 11111111.

Converted from binary to decimal, this value can be from 0 to 255 (the limitations of an 8-bit binary converted to decimal).

A complete IP address in binary notation will look like this:

10101100.00010000.01010001.01100100 (4 octets)

Imagine having to repeat all 32 numbers each time you have to reference your IP. Pweh! Yeah, tough! Even our home address postal codes can be tough to remember! But don't stress. Even though the computer only understands binary, that does not mean we are forced to use it. Each octet is converted to decimal for our convenience and separated by a period. We communicate IP addresses using the dotted decimal notation.

The above binary IP address will typically be converted to and represented in decimal notation as:

Subnet Masks

As we discussed earlier, IP addresses identify computers the same way mailing addresses identify our homes. The internet is the largest network of networks. As such, the IP addresses indicate to the routers (the networking devices used to forward packets from one computer or node to the other) the right network (network address), which in turn would lead it to locate the right computer or device (IP address).

To unlock this lesson you must be a Member.
Create your account

Register to view this lesson

Are you a student or a teacher?

Unlock Your Education

See for yourself why 30 million people use

Become a member and start learning now.
Become a Member  Back
What teachers are saying about
Try it risk-free for 30 days

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.

Create an account to start this course today
Try it risk-free for 30 days!
Create an account