A visitor management system is a formal way in which you can manage the usage of your building and the movement of visitors. More and more busiensses are opting for a Visitor Management System like the ones offered by https://www.ofec.co.uk/web-and-software-development-services/digital-visitors-and-staff-signing-in-book.aspx to remove the need for staff to physically sign people into the building.
This works well in terms of GDPR in that data is stored on a computer or tablet so that paper copies of information are not left lying around. It also helps to allow receptionists to carry on with other tasks. It gives a log of those people that have visited your premises which could be useful in terms of marketing if you ask for their permission to keep them up to date with your business and can also be used for security purposes.
Schools in particular use this type of system so they can account for visitors if a fire evacuation is needed and also track visitors and keep a record of who was in and out of the building should an investigation of some sort need to take place. They can be used as evidence in the event of parking fines in restaurants as well.