The "T" is Boston-speak for the local subway network. This network directly touches Somerville on the Red line stops of Porter and Davis, serving (you guessed it) Porter Square and Davis Square. At the other end of town, the Orange line stops here in Somerville at Sullivan Square. Those living near Union and Inman Squares can walk or take a short bus ride to Central Square (Red line) or Lechmere (Green line).
Each of these lines will move you from Somerville to Cambridge, Boston, Brookline, and points beyond, as the map shows.
For pricing and route info, check out the MBTA website.
Bump-n-grinding with other cars is just not that fun (or friendly). So, just like with the rest of Boston, don't drive if you can help it. Boston's subway system, the 'T' will get you most places and within a short walking distance of much more. The 'T' is operated by the Massachusetts Bay Transit Authority (MBTA) and you can check them out on the web at http://www.mbta.com.
Located on the Western banks of the Charles River just behind Cambridge, Somerville is serviced by the Red and Orange Lines of the 'T', Boston's subway system. The Red Line stops at Porter Square and Davis Square while the Orange Line hits Sullivan Square.
Other than the 'T', cabs are fairly easy to obtain, but try to get a cabbie that is local to the area, especially if you aren't sure where you are going. The Green Cab company of Somerville is good as they can get you just about anywhere on minimal information. Just don't expect a downtown Boston cab company to know the local joints or how to get to them.
If you're in Boston you don't need to drive. The T is excellent, as is the bus system and commuter rail. Some people enjoying around the Boston area. Boston (Somerville) has heavy traffic, so be careful if you're going to bike!!!