Although for locals car ownership is a highly desirable sign of success and social status, St. Petersburg's public transport network is actually extensive and efficient, if often overcrowded. The metro is undoubtedly the best bet for visitors, and covers nearly all of the city, with new stations opening almost every year. It also has some spectacular station architecture.
Overground transport is bewilderingly varied, but not difficult to use with the help of a few pointers (see individual pages below), and St. Petersburg's latest transport project means that you can even use the city's waterways to get around. The only real disadvantage of the public transport system is the lack of nighttime services, so if you plan to stay out after midnight, you will have to rely on taxis or your own two feet to get home.
Fares for all forms of public transport are comparatively low (around $1 or less for any single journey), but if you are staying in the city for longer than a week, it is probably worth investing in a travel card (see below for details).