# What is Conversation Thread?

Also called Thread, Conversation History.

A conversation thread is the ordered sequence of messages that belong to a single exchange, together with the identifiers that keep them grouped. Threads give an assistant the history it needs to interpret references such as 'that one' or 'the second option.' Platforms implement threading differently, from email headers to explicit thread objects in chat systems.

Grouping is a platform concern. Email uses Message-ID, In-Reply-To, and References headers, and clients still disagree about how to treat a changed subject line. Chat platforms usually expose an explicit thread identifier. Phone calls have no native thread at all, so continuity has to be constructed from the caller's identity and a stored record of previous contacts.

For a model driven assistant, the thread is the working context. Which prior turns are included, how many, and whether older ones are summarized directly determines whether the assistant resolves a pronoun or asks a question it already asked. Because context length is finite, long threads need a strategy: keep recent turns verbatim, compress older ones, and retrieve older detail on demand.

Two errors recur. Merging distinct topics into one endless thread makes retrieval worse and leaks context between unrelated requests. Splitting a continuing exchange into new threads makes the assistant amnesiac and forces the customer to repeat themselves. Threads also accumulate personal data over time, so retention and deletion are usually defined at thread level rather than per message.

Threads and conversations are not the same object everywhere. One customer case can span several threads across channels, and one long thread can contain several unrelated cases. Systems that conflate the two produce confusing history, which is why an omnichannel record usually sits above threads rather than replacing them.

## Key points

- Ordered messages plus the identifiers that group them
- Email threads by headers; chat platforms use explicit thread IDs
- Phone calls have no native thread, so continuity is reconstructed
- Long threads need summarizing or retrieval to fit context limits
- Retention policy is usually defined at thread level

## In practice

A customer emails about a refund, replies twice over four days, then writes 'any update on this?' with no other detail. Because her mail client preserved the reply headers, all four messages sit in one thread, so the assistant knows which refund is meant, which order it concerns, and what was promised on day two. Had she written from a new address, the thread would have broken.

## Related terms

- [Turn](/en/glossary/turn)
- [Omnichannel](/en/glossary/omnichannel)
- [Inbound Email Parsing](/en/glossary/inbound-email-parsing)
- [Chatbot](/en/glossary/chatbot)
- [Channel Routing](/en/glossary/channel-routing)

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