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# Store and reference chat history
The ConversationalRetrievalQA chain builds on RetrievalQAChain to provide a chat history component.

It first combines the chat history (either explicitly passed in or retrieved from the provided memory) and the question into a standalone question, then looks up relevant documents from the retriever, and finally passes those documents and the question to a question-answering chain to return a response.

To create one, you will need a retriever. In the below example, we will create one from a vector store, which can be created from embeddings.

import Example from "@snippets/modules/chains/popular/chat_vector_db.mdx"

<Example/>
