Home-link is the button that is in your car that your remote clicker can be programmed to. This works for most cars, but not all. Home-link does not require batteries but it does require a programmed clicker to the existing gate or garage to create a home-link connection.
If your home-link stops working, you will need to reprogram it with your programmed clicker. Not often, but sometimes home-link forgets the programming due to using what is known as “rolling code” technology.