The Société de transport de Montréal (STM) operates both the métro (subway) and the bus system. The métro is clean and quiet (it runs on rubber tires), and will get you to most of the places you want to visit. For those few places that are more than a 15-minute walk from the nearest métro station, bus connections are available.
Métro hours on the Orange, Green, Blue, and Yellow lines are weekdays 5:30 am to 12:30 am and weekends 5:30 am to 12:30, 1, or 1:30 am (it varies by line). Trains run every three minutes or so on the most crowded lines—Orange and Green—at rush hours. The cash fare for a single ticket is C$3. One- and three-day unlimited-use cards are also available for C$9 and C$18.