Priority boarding on United Airlines is available to eligible passengers based on their cabin class, frequent flyer status, and qualifying benefits. Moreover, knowing the available options helps flyers arrange a much smoother boarding experience. To know who qualifies for priority boarding united, check the following categories. 
Premium Cabin Flyers: United First and United Business passengers generally receive priority boarding.
Premier Members: Eligible MileagePlus Premier members receive earlier boarding privileges.
To get detailed information about the boarding groups, one can go through the online portal of United Airlines or click the above link provided by Group Travel Airlines.
Read more: https://grouptravelairlines.webflow.io/posts/united-boarding-groups-a-comprehensive-guide