Many, many Stockholm visitors opt to use public transportation as a means of getting around the city.  The public transportation system is operated by Lokaltrafik (http://sl.se/en/Visitor/ - look for the interactive travel planner) and includes a bus, train and subway system.  Visitors should strongly consider purchasing a 72 hour or weekly Access Card ticket, which offers unlimited ride access to all modes of public transportation and makes getting to anywhere in Stockholm and easy and inexpensive process.

The most usual method of getting around via public transportation is the subway system, also known as The Metro, The Tunnelbana and the T-bana.  This system is reported to be safe, clean, and efficient.  Travelers who want to get from one destination to another quickly often choose this method.  However, because this is an underground system, visitors are not able to see the sights while traveling this way. The system operates from about 0500-0030 on most days, and all night on Friday and Saturday nights. On the central stretches, trains generally arrive every few minutes, while you may have to wait 10-15 minutes (even longer early morning or late evening) to go to a far-flung destination. There are three main lines, which divide into further branches away from the centre. 

The commuter train (pendeltåg) is also fairly frequent. The stops are much more widely spaced than the T-bana, and travel between them is quicker. It extends about 50km from central Stockholm. The sign denoting pendeltåg stations is a J.  

Buses tend to go pretty much everywhere. It's worth noting that they are a lot slower to get around the centre than other modes of transport, as they take rather indirect routes to fill in the space between the T-bana lines. 

There are several light rail lines that run to more isolated suburbs or offer shortcuts between different parts of the city, while there is also one tram line. Tram 7 runs from Sergels Torg to Waldemarsudde and passes through a large number of the most popular tourist attractions.

A nice way to travel in Stockholm is by boat, especially the ferry between Slussen and Djurgården, a big island with Skansen, the amusement park Gröna Lund, the children's Astrid Lindgren World and several other museums. The trip is also a cheap way to experience a part of the water that makes Stockholm special. There are also boats to Fjäderholmarna, Drottningholm Palace and other places outside Stockholm.

Visitors interested in learning more about the various public transportation options in Stockholm can see reviews of these options online at http://www.virtualtourist.com/travel/... .