The host key is a 6-digit PIN tied to your Zoom account. It is not meeting-specific. You can use your host key to claim host privileges in the following circumstances:
You have Join Before Host enabled and the host joins the meeting without signing in
The host joins the meeting via telephone
The host joins the meeting through an in-room video conferencing system (an H.323/SIP device)
You can customize your host key on your Zoom Profile page. Since the host key is tied to your account rather than to a specific meeting, you should not tell anyone else your host key. Treat your host key like a password. If you do share your host key, you should change it immediately. We also recommend changing your host key periodically as a security best practice.
For instructions on how to customize your host key, and how to use it in the circumstances above, see the Host Key article on Zoom Help Center. Note that "PSTN-only Personal Audio Conference (PAC) meetings" are not supported in the UMN Zoom platform.