IP-Protocol

The Internet Protocol (IP) forms the foundation of all communication on the Internet. It handles the addressing and forwarding of data packets between networks—the "navigation system" of the digital world, so to speak.

When a computer sends data, it has to get from A to B somehow. The IP protocol assigns each data packet a sender and a destination address—similar to an envelope. These addresses are called IP addresses, for example, in the form 192.168.1.1 (for IPv4).

However, IP itself doesn't care whether the packets arrive in the correct order or whether all packets are delivered at all—it's connectionless and stateless. This means it simply sends and leaves the rest to other protocols (e.g., TCP or UDP). It's comparable to sending a letter: The post office often delivers it to its destination, but it doesn't guarantee that it will arrive complete or quickly.

IPv6 – the modern version:

Because the approximately 4.3 billion possible IPv4 addresses have now largely been assigned, IPv6 was developed. It uses significantly longer addresses – e.g. 2001:0db8:85a3:0000:0000:8a2e:0370:7334 – allowing a virtually unlimited number of unique devices on the Internet.
IPv6 also brings improvements in packet structure, automatic configuration, and security – however, it has not yet been fully implemented everywhere, so IPv4 and IPv6 are often used in parallel.

What is important is:
Without IP, data packets wouldn't know where to go – and routers wouldn't be able to forward them across the global network. That's why IP is at the heart of the TCP/IP reference model – the foundation of all communication over the Internet.

Classification in the OSI model:

• Network Layer (Layer 3)
  The Internet Protocol (IP) is placed in the network layer because it is responsible for addressing and forwarding data packets across network boundaries. It determines the path a packet takes through the network, but has no knowledge of connections or content.