On your Interrail trip you may have to cover certain routes by bus. There can be many reasons for that: on some routes the bus is quicker than the train (eg Prague to Munich) and on some routes there is no direct train connection available (eg Sevilla to Faro or Sarajevo to Belgrade).
Some train companies also offer long distance bus connections, usually named „Intercity Bus“. The largest network of IC Buses is operated by DB (German Railways) who run many domestic and international services to destinations such as Prague, Zagreb, Copenhagen and even London. Other IC Buses are operated by CD (Czech Railways) on the route Ostrava – Krakow and by ÖBB (Austrian Railways) on the routes Graz – Klagenfurt and Klagenfurt – Venice. These buses usually provide direct connections between cities where there is no direct train service and are faster than available connecting train services. Interrail is valid on board all of these IC services, however they usually require a seat reservation.
Besides these long distance IC Buses there are also a number of local bus services provided by train companies which also can be used with Interrail. The most important of these service are the bus between Rijeka and Lupoglav operated by HZ (Croatian Railways) which connects the railway line to Pula with the rest of the Croatian network and the bus services of SNCF (French Railways), for instance from Oloron to Canfranc and from Digne to St Auban and Veynes. Another important bus link is the line from Lulea via Tornio/Haparanda in Finland, linking the Swedish and Finnish rail networks. Interrail tickets are valid on this line which is operated by local bus companies.
Of course there are many more long distance bus lines available throughout Europe. However, since we at railcc prefer to travel by train if possible we are only going to feature bus connections where they complement the existing railway network and cover routes which are not possible or too time-consuming by train.