EuroCity (EC) trains are daytime international services operated within the European inter-city rail network. All EC journeys take place between 6am and midnight, as opposed to the night-train alternative, EuroNight.
EuroCity trains travel through two or more countries on their journey, stopping only at major cities, for generally no more than five minutes. They are generally not high-speed services, but still travel at speeds of over 90km/hr.
Depending on which countries you are travelling between, the actual carriages used by the EC service will vary. For example, if you are travelling through Germany, chances are that your train will use Deutsche Bahn rolling stock. As such, the quality and options available to you will vary depending on which route you are taking.
Seat reservations on EC trains are not compulsory, but are recommended, especially for more popular routes. Seat reservations cost a supplement of €4 per person, per leg.