InterCity trains were among Trenitalia's faster trains until the Frecce trains came along. They still connect more destinations than the Frecce or Italo high-speed trains, so they can be either an economical option (they're usually less expensive than the high-speed trains) or the only option.
InterCity (IC) trains travel at speeds of up to 100-125 MPH (160-200 km/h), and there are first and second class cars. While reservations for IC trains are required, if you purchase a ticket online or at the train station the reservation is included automatically. Rail passholders, however, are not required to have a seat reservation before boarding IC trains, though seat reservations can be purchased in advance.
There are currently 86 daily InterCity connections throughout Italy, reaching more than 200 stations.