Networking history and services: In classic online systems, what is a “bulletin board system (BBS)”?

Introduction / Context:
Before today’s social media and cloud forums, hobbyists and organizations hosted Bulletin Board Systems (BBSs) that users dialed into with a modem. Understanding what a BBS provided helps place modern messaging and file-sharing platforms in historical context.

Given Data / Assumptions:

• Users connected via telephone lines using dial-up modems.
• BBS software ran on a host computer answering incoming calls.
• Services typically included message boards, file libraries, and sometimes games.

Concept / Approach:
A BBS is fundamentally a public (or semi-public) access message and file-sharing system. The modem is merely the access device at the user and host ends; the BBS is the software/service offering message posting, threaded discussions, mailboxes, and downloads/uploads under operator policies (sysop).

Step-by-Step Solution:

Verification / Alternative check:
Period manuals for popular packages (e.g., Synchronet, WWIV) describe message subsystems and user moderation—not signal conversion hardware roles.

Why Other Options Are Wrong:

Common Pitfalls:
Equating dial-up access hardware with the service; overlooking that some BBSs were private but functionally the same system.

Final Answer:
is a public access message system.