Does the fence have posts? These will be set at the boundary line, and the rails set so that the fence boards/panels are also right on the boundary.
Posts are usually wider than the fence panels so the flat (neat) side of the fence faces outwards to face your neighbour. Your side will have the posts clearly visible. But this way you get to have as much of your land available to you to use. The person who puts up the fence is responsible for it. If you put up a fence you will want to keep as much of your land as possible so convention is if yo can see the posts you own it.
Posts are usually wider than the fence panels so the flat (neat) side of the fence faces outwards to face your neighbour. Your side will have the posts clearly visible. But this way you get to have as much of your land available to you to use. The person who puts up the fence is responsible for it. If you put up a fence you will want to keep as much of your land as possible so convention is if yo can see the posts you own it.