Herat is one of the safer cities in Afghanistan. However, there are sometimes small explosions attributed to political parties which are trying to make a point or create the impression that the city is not safe. Shootings are also common during personal disputes. Gun battles between the Afghan National Army and Afghan National Police are not unusual.
respect
Be quiet, respectful and dress appropriately when visiting mosques and shrines. These are holy places of worship and should not be treated as tourist attractions. Be discreet with your camera.