Ball marks, shoe damage such as spike marks and scrapes or indentations caused by equipment or a flagstick are regarded as damage to the putting green and therefore may be repaired. Also included would be old hole plugs, turf plugs, seams of cut turf and scrapes or indentations from maintenance tools or vehicles, animal tracks or hoof indentations, and embedded objects such as a stone, acorn, hail or tee and indentations caused by them.
If your ball or ball marker is accidently moved by yourself or another player there is no penalty but make sure to replace the ball back on its original spot, which if not known must be estimated.
I was asked recently by a reader why replacing divots is essential and perhaps at the top of the list in golf's etiquette. These are the main reasons: to speed up the recovery process, and ensure a smooth, level playing surface for the course. Properly replaced, intact divots can take root in days, whereas ignored ones create uneven, unsightly, and slow-healing bare spots that act as hazards. Replacing the original, intact turf with soil attached allows it to immediately knit back together, speeding up recovery compared to leaving a bare spot which would be unfair for other players. A replaced divot seals the soil, stopping weeds from growing in the damaged area.
Out of Bounds: "Golf is the loneliest sport. You're completely alone with every conceivable opportunity to defeat yourself. Golf brings out your assets and liabilities as a person. The longer you play, the more certain you are that your performance is the outward manifestation of who, in your heart, you really think you are.