Rome has buses, trains, trams and a metro system, all serviced by ATAC. ATAC stands for Azienda per i Trasporti Autoferrotranviari del Comune di Roma, the transport agency of the municipality of Rome.
On a daily basis, I get to and from places by walking, riding the bus or using the metro. I walk to school, ride the bus to volunteering and ride the metro home. On the weekends, I frequently take the bus and metro to other rione (historical neighborhoods) and quartiere (neighborhoods) further away from where I live. There are many different buses and bus routes here in Rome. So many, in fact, that I don't think I will end up riding even half of them by the time I leave. However, there are only two different metro lines.
The way people get around depends mostly on how far away they live from where they work and where they go to school. I am very lucky that I am able to simply walk to school. My host sister, however, has to ride the bus for 45 minutes every morning and afternoon to go to and from her high school. One of my teachers lives far enough away that he has to take a train and a bus to get to class.