International high-speed train service operated jointly by the French, Belgian, Dutch and German railways, connecting Paris (Gare du Nord) with Brussels Midi/Zuid and then on to Amsterdam CS and Köln Hauptbahnhof. Additional services - some seasonal - extend to Düsseldorf, Ostend, Namur, Marne-la-Vallée (for Eurodisney), the French Alps, Marseille and Geneva.
Of the core Thalys routes, at present only the section between Paris and Brussels (splitting off from the the TGV Nord line near Lille and crossing the border near Tournai) runs on dedicated high-speed tracks; the 300 km journey takes an hour and 25 minutes; travel on the remainder of the services is at normal running speeds except for the extended services in France via existing TGV lines; work is in progress on the lines into Germany and the Netherlands. Most services run the Brussels-Paris section combined and then split into one set for Amsterdam and one for Köln. Special ticketing arrangements and fare supplements apply, but the prices can be quite cheap, particularly at weekends.
The trains themselves are a further development of the TGV design, similar to the Eurostar trains but in shorter sets and without the multi-voltage setup required for running in the UK, and painted in a fetching shade of maroon.
Timetables and stuff are predictably available via http://www.thalys.com