Users have a Drafts feature available to them, which periodically saves a temporary copy of a post you are writing as you are creating it. The benefit of having drafts enabled is that in the event that you accidentally leave the posting page before making your post, you will be able to restore the message that you were typing so that you can finish it rather than having to start all over again from scratch.
The way this works is if you begin to type out a post on the forum and leave the posting page, when you return to the topic a popup will appear letting you know that a recent draft that you were working on has been found. This pop-up will show a preview of the message that the system saved up to, and from there you can choose whether or not to restore the draft so that you can finish making your post. Keep in mind that only one draft is saved, and this feature is meant for emergency purposes to help restore the most recent post that you were working on as it's needed
To enable the drafts feature, click the Profile button found in the top menu bar of the forum, and then on your profile page click the Edit Profile button. You will then be taken to the Edit Profile & Settings page for your account; once here, click on the Settings tab. When the page loads, you'll find the Enable Drafts located as the fourth option on the page. Set this to Yes and save the changes. Once this is done, drafts of your posts will be saved so that you can restore from them as they are needed.