Fences make good neighbours
Neighbours are liable for half of the cost of an ‘adequate’ boundary fence. In most rural situations this is a standard 7-wire post and batten fence. However, it is best to discuss this and decide on a mutually agreeable fence and work out the cost before you start anything.
There are always exceptions where you’ll negotiate. For example, if a boundary is across a flood plain, you might want to do a three-wire fence with no battens. If you or your neighbour have different livestock – they have cows, you have goats – you will need to compromise on wire vs mesh.