Trondheim's international airport has connections to some international destinations. This includes Amsterdam with KLM, Copenhagen with Widerøe, and Prague, Slit, Dubrovnik, Salzburg, Malaga, Riga, London and Nice with Norwegian.
Local trains Steinkjer–airport–Trondheim and Trondheim–Røros are operated by NSB.
For local buses in Sør-Trøndelag including Trondheim, search atb.no
There are some local passenger boats. Use the same site as for local buses.
There is an extensive road network, however often fairly curvy and slow.
To cross fjords, there are several bridges and tunnels, but some car ferries also exist. They have fees, but there is no need for booking. Some roads, especially new tunnels, and all entrances to Trondheim have road tolls.