Helsinki is an exceptionally safe, highly functional capital city. Violent crime is extremely rare, and walking at night is generally very safe, even for solo travelers. Like much of Scandinavia, it is largely a cashless society. The primary hazard for visitors is the winter weather. From November to March, sidewalks can be covered in 'musta jää' (black ice), making walking treacherous without proper winter boots with strong grip. Additionally, tourists must be vigilant around the city's extensive tram network; trams are very quiet and have the right of way, so always look both ways before crossing the tracks. During the dark winter months, wearing small reflective tags on your clothing is highly recommended and expected of pedestrians.