Expand and explain the following terms:

(a) PPP

(b) POP3

(c) VoIP

(d) IRC

(a) PPP — Point-to-Point Protocol (PPP) is one of the most commonly used data link protocols. It is utilized to establish a direct connection between two nodes and can provide various functionalities such as connection authentication, transmission, encryption, and compression. Communication occurs through a high-speed modem, and PPP is used to connect telephone dial-up lines to the internet.

(b) POP3 — Post Office Protocol version 3 (POP3) is a simple and standard method for accessing mailboxes and downloading messages to local computers. Users can receive messages using the POP3 protocol. An advantage of POP3 is that once messages are downloaded, an internet connection is no longer necessary to read the mail, as they are saved on the computer's hard disk.

(c) VoIP — Voice over Internet Protocol (VoIP) is utilized for transmitting voice communications. Voice calls undergo digitization, compression, and fragmentation into small packets, which are then transmitted across Internet Protocol (IP) networks. VoIP implementation allows users to carry voice traffic efficiently over an IP network.

(d) IRC — Internet Relay Chat (IRC) is an application layer protocol that enables users to share text messages. The sender sends a request to an IRC server, which then forwards the request to another client, facilitating communication between users.