Introduction
In late 2021, the Discourse project introduced Chat as a beta. By now, Chat has been launched as part of the default stable release of Discourse and has been enabled on our forum ever since.
Can I use it?
You may ask yourself, where is it then? Chat is just like DMs (direct messages) only available when you reach trust level 1 (TL1). This trust level can be reached by being active on the forum for about 15 minutes.
This limits spammers and trolls to pollute our community. Chat and DMs are harder to moderate due to the faster interaction and free flow of subjects. By setting this threshold to; trust but verify someones intent, it makes the moderation much easier. Also, new users might not want to be exposed to all the features at once, so gradually introducing them to new ones makes the learning curve less steep. As you progress your trust levels, more features will become available.
If you have reached TL1, then you can open the Chat 
Chat history
The chat history in the channels are set to expire after 90 days. This is because no matter how you design your chat with bots and multiple channels, information gets lost after a certain period. Usually once the chat messages leave the screen space. This chat expiration motivates people to keep creating topics so that information will stay categorized and easy to find. You can also move chats into a topic which makes these chats persistent.
Personal chats do not expire, only the chat channels.
Move a chat into a topic
You can easily fork a conversation into a topic. This can be a single chat message, or a selection. Click on the 3 dots when you either long press a chat on a touch controlled device, or when you hover over a chat with your mouse. Then click on the three dots, click on select and then when you finished selecting all the chats, click on quote to topic. This will open a topic in draft mode, from there you can create your topic with the chat messages as a reference. This will make chats persistent.