Can my neighbour come on to my property without my permission?
They regularly walk across my front yard. It’s worn a track in my lawn.
Your neighbour may believe they can come onto your property to deal with a problem — a leaning fence, a noisy sprinkler, a bothersome tree, and so on. But if they do so without your permission, they’re trespassing. If they refuse to leave when asked, you can call the police.
If some part of the neighbour’s property — say a tree, fence, or other structure — crosses over the property line, that’s also a form of trespass.