Explanation:

To join the internet, a computer needs to be connected to an internet service provider (ISP). An ISP is a company or organization that provides access to the internet.

Reasoning:

The internet is a global network of computers that are connected to each other through various networks. To access the internet, a computer needs to establish a connection with an ISP, which acts as a gateway to the internet.

Elaboration:

1. Internet Architecture Board (IAB): The Internet Architecture Board (IAB) is an advisory body that provides guidance and oversight to the development of internet standards. It does not provide direct access to the internet for computers.

2. Internet Society (ISOC): The Internet Society (ISOC) is a non-profit organization that promotes and supports the development and use of the internet. While the ISOC plays a crucial role in shaping the future of the internet, it does not provide direct access to the internet for computers.

3. Internet Service Provider (ISP): An ISP is a company or organization that provides internet access to individuals and businesses. ISPs connect their customers to the internet through various technologies such as dial-up, DSL, cable, fiber-optic, or wireless connections. They also offer other services like email, web hosting, and virtual private networks (VPNs).

When a computer is connected to an ISP, it is assigned an IP address, which is a unique identifier on the internet. The ISP routes the computer's internet traffic to the appropriate destinations on the internet and handles the communication between the computer and other devices on the internet.

In conclusion, to join the internet, a computer needs to be connected to an internet service provider (ISP) that provides the necessary infrastructure and connectivity to access the internet. The ISP acts as a gateway, allowing the computer to communicate with other devices and access resources on the internet.