MAC Address and IP Address Differences

It is true that the need for IP addresses is questionable because they are given unique MAC addresses all over the world.However, it is correct in terms of "identifying things", but not in order to deliver information.

Often described, the IP address identifies the source/final destination and the MAC address identifies the next machine to be forwarded.

You need to know the difference between L2 (data link layer) and L3 (network layer).

The L3 IP address allows the organization to design allocations to some extent freely, allowing the organization to determine the size of the network, the network next to it, and the network upstream.You can include the size and usage of your organization, the contract with the shipping address, and the circumstances of adults.

The L2 MAC address is assigned by the vendor for each device, so there is basically no room for user reasons.
In addition, you can only communicate with MAC addresses in the local network.This is because even if you send information to a destination MAC address, it becomes congested in networks that cannot reach the correct destination until you send it to machines around the world, and L2 is a closed world without the concept of a neighbor network.

You might have wanted to create a network that communicates with MAC addresses all over the world, but TCP/IP, which is not the mainstream today, uses the L2/L3 protocol stack to share roles.

The so-called The Internet uses Internet Protocol, which identifies equipment by IP address. Mac address is not required.In fact, it's completely out of fashion now, but for PPP connections via modem/acoustic couplers over telephone lines, the PC side uses a serial port, so there's no Mac address.

So the answer to the question is
Q1. Why does the IP address exist?
A1. It is designed to distinguish between devices on the Internet/Intranet

Q2. Why does the MAC address exist?
A2. Exists as an Ethernet specification.

Q3.Why do you use IP addresses when you have MAC addresses?
A3. Internet Protocol is now commonplace for Ethernet devices (with MAC addresses), but it can also be used for other devices (such as modems) (without MAC addresses).Therefore, when using Internet Protocol, identifying the other person from a program perspective always uses only the IP address.