Access control is a modern replacement for keys and locks.
It takes over where keys and locks fall short by allowing you to control the flow of personnel through your building and keep a record of who goes where and when. It lets you redirect personal access as situations change and access authorization is redefined. It will allow you to make a persons key inactive when they leave your employ without the expense of changing locks or being worried about unauthorized entry. You can control elevator floor access or air conditioners. You can secure your building knowing that if unauthorized entry is made, it will be reported and if authorized entry is made, it will be recorded in a permanent log which can be used for reports of who was in your building and when.