zulip/templates/zerver/help/include/streams-and-topics.md

In Zulip, streams determine who gets a message. Topics tell you what the message is about.

Topics are light-weight subjects, very similar to the subject line of an email. Like in email or a forum, messages about the same topic are shown together as a conversational thread. Here is what it looks like in Zulip.

Topics are one of the most wonderful aspects of using Zulip:

• Lots of conversations can happen in the same stream at the same time, each in its own topic. You never have to worry about interrupting — each conversation has its own space.
• Conversations can last many hours or days, letting everyone respond in their own time. Don't worry about replying long after a message is sent — everyone will see your reply in context.

Check out Why Zulip to learn more about how Zulip's topic model helps transform how your organization communicates.