Your local IP address is different from your external IP address. It is the address your device is associated with in your local network.
An IP Address is a unique identifier that is allocated to a particular device. This is used in order to identify the device and allow it to communicate with other devices via the internet (with external networks) or intranet (within a local network). These devices can range from mobile phones, tablets, PCs, desktop computers, laptops, printers, and any other device that supports the Internet Protocol (IP).
IP Addresses have two formats IPv4 and IPv6. IPv4 is 32 bits; these are the traditional IPs that have been used since the beginning of the internet, just like 18.104.22.168. Another type of IP is IPv6, which is 128 bits in size and looks like 2001:0db8:85a3:0000:0000:8a2e:0370:7334. IPv6 was introduced to cater for a larger number of IPs because a greater number of devices (also known as Things in-terms of Internet of Things-IoT) needed to be assigned an IP.
It is important to understand the difference between private and public IP addresses. Private IPs are ones which are not accessible from the internet and are used in internal networks, like the IP of your desktop. Some IP ranges have been fixed globally and are used as private addresses (Class A, Class B, and Class C).
On the other hand, public IP addresses are accessible by the whole world through the internet. The simplest example of a public IP address can be an IP address of a website(s).
Google.com uses 2a00:1450:4006:801::200e as one of its public address.
A Local IP address is the identifier (IPv4 or IPv6) that is assigned to your laptop, PC, mobile and any other device within your local network. It is not visible to the outer world, but it is required in order to use the internet.
Your router assigns an IP to your mobile phone, one IP to your PC, one IP to your printer or even camera.
This assignment of IP Addresses is mostly done by a protocol called DHCP (Dynamic Host Configuration Protocol).
There was a time when finding a local IP address from the internet was considered difficult. Now thanks to certain apps and protocols, we can find a local IP address with ease, most commonly with WebRTC (Web Real-Time Communication).
In order to understand the role of a local IP address, let’s look at an example of internet browsing.
Our home router assigns a unique IP address (commonly known as a local IP address) to every connected device. When we look for some website:
2. Then, this request reaches the ISP Router, they have another IP which talks to the internet through a Public IP.
Once there is a response from the website, how does an ISP know where to return this request?
1. The ISP Router gives this request back to your home router, based on your Router IP, and then
2. Then, the home router provides the information to your device based on the local IP Address.
This idea of translating/mapping the IPs between private IP and public IP is commonly known as Network Address Translation(NAT).