Hyatt Hotels and Resorts typically require that at least one guest in the room is at least eighteen years of age to check in. However, this age requirement may vary depending on the specific hotel and its location, as some properties may have different policies that allow those younger than eighteen to check in if they are accompanied by a parent or guardian. It is advisable to review the specific terms and conditions of the hotel where you plan to stay, as this information is generally included on the hotel's website. Additionally, some hotels may have specific arrangements for travelers who are part of special programs or events, which could influence the age policy. For the most accurate and detailed information regarding age restrictions, it is best to consult the specific Hyatt hotel’s webpage or the current booking terms located on hyatt.com.