Final answer:
To begin a chat session, a program known as a chat client is used to connect to a chat server. This allows for real-time text messaging and other features like file transfers and calls.
Step-by-step explanation:
To start a chat session, you connect to a chat server through a program called a chat client. This client software is responsible for establishing a connection with the chat server and transmitting your messages. Most modern chat clients offer a variety of features such as file transfer, voice and video calls, as well as text messaging. Using this software, you can engage in real-time communication with other individuals who are connected to the same server, creating a virtual space for conversation and collaboration.