An IPv4 address on the internet is a unique numerical label assigned to each device connected to the internet using the Internet Protocol version 4 (IPv4) protocol. It serves as a unique identifier for devices, allowing them to send and receive data across the internet.

IPv4 addresses are 32-bit binary numbers, represented in a human-readable dotted-decimal format using four sets of numbers separated by periods (e.g., 192.149.252.76). Each set is called an octet, represents 8 bits, ranging from 0 to 255. This allows for approximately 4.3 billion unique IPv4 addresses.

These addresses are essential for devices to communicate on the internet. When you access a website, send an email, or stream a video, your device uses its IPv4 address to connect to the desired server or device and transfer data back and forth.

The Significance of IPv4 Addresses: IPv4 addresses play a pivotal role in enabling communication between devices over the internet. Just imagine the internet as a massive network of roads. Each device on the internet needs a unique address, much like a house on a street, to be able to send and receive data. IPv4 addresses provide this essential identification, ensuring that data reaches the correct destination.

However, due to the exponential growth of internet-connected devices, the supply of available IPv4 addresses has become limited. To address this issue, IPv6 (Internet Protocol version 6) was introduced, offering a much larger address space to accommodate the increasing number of devices. IPv6 addresses are 128-bit binary numbers, represented using hexadecimal notation, and provide an almost limitless supply of unique addresses.