Boston has a reasonable public transportation system and you will be using the subway system regularly while attending the conference. There are 4 major lines identified by color (Red, Green, Orange, Blue) plus the weird Silver Line which is really a bus. There are clear signs inside the subway stations but you might want to print or pick up a map of the system (here's a PDF), it will be handy. The section of the Green Line between Park Street and Boylston was the first in the United States and it definitely is showing its age. Think of it as character.
To ride the subway you will need a Charlie Card or a Charlie Ticket.
- Charlie Cards are plastic, you can add value to them with cash or credit card on machines located in all subway stations. Each ride on a Charlie Card costs $2.25. You can get a Charlie Card at the more major subway stations, here's a list.
- If you don't have a Charlie Card you can buy a Charlie Ticket at the machine in any subway station. Charlie Tickets are paper and can be bought by cash or credit card and loaded with single or multiple rides. They are not rechargeable. Each ride on a Charlie Ticket costs $2.75. That's more expensive so you should get yourself a Charlie Card as soon as possible.
If you arrive in Boston at Logan Airport you will be able to take public transportation into the city for free, no need for a Charlie Card or buss fare. Silver Line buses make frequent stops at all terminals, and will carry you to South Station where you can transfer to the subway system. Be sure to pick up a Charlie Card when you pass through South Station (if it's between 7 AM and 7 PM).