Horizontal lines on the neck is pretty common and there are several reasons for their appearance. Like your face, the skin on your neck is also quite delicate.
Though we take ample care of our face, neck is often ignored until we notice something like this. Skin which has started to age will also show lines on the neck. These are also known as neck wrinkles and they can appear at any age. It is important to do something about it before they become more prominent.