You likely hear the term IP address fairly regularly whether its at work or when watching TV, but what does it actually mean? In this video we're going to look at what an IP address is and what's its used for.
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An IP address is a string of numbers assigned to all internet connected devices and separated into four sections by dots with each section being known as an octet. This is used to identify your computer on the internet so any data that's meant for you arrives to your device and not another random device somewhere else in the world. A useful comparison is to think of an ip address like your home address if you send a letter to a friend you'll put your address as the return address on the back of the envelope to ensure they know where to send the reply
This is essentially what happens when you're sending a request for data to another device on the internet. You clicking this YouTube video sends a request from your device to your router and then out onto the internet to a youtube server the youtube server then uses your ip address to send the data back to your router and to your device and you're now watching the video. There are two types of ip address a public ip and a private ip.
A public ip is the ip address of your gateway to the internet in most cases this is a router. The address is completely unique and not shared by any device in the world. this is the address that your router will use to send and receive data to and from the internet. Due to the structure of ip addresses which will be covered in a future video, there are 4 billion 294 million 967 296 unique public ip addresses and if you take into consideration that there are over 7 billion people on earth you can quickly see an issue.
Many people will own at least five internet connected devices so why haven't we run out of ip addresses yet?
This is where private ip addresses come in, they were created in an effort to stop us running out of public ips. A private ip is the address of a host or device on a network. The first three octets of the address are the network and will be shared by all devices on that network, the last octet is the host or device because your device has to have a unique ip on your home network so your router knows which device to send the data back to.
If you visit a friend's house and check the ip addresses of devices on their home network you may find the ip addresses are the same as some of your devices on your home network. Private ip addresses do not need to be unique as long as they are connected to different networks. This stops us needing to use a unique public ip for every device in the world which would have caused us to run out of public ips years ago. if we go back to our earlier diagram we can see how public and private ip addresses are used, you click a youtube video and the data is sent from your device with a private ip to your router which uses network address translation to send the data out onto the internet using its unique public ip.
The youtube server then uses your public ip to ensure the data is sent back to your router which then uses network address translation again to send the data back to the device that requested it using its private ip which is unique to that home network
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