Should I file a national, European or international application?
When seeking patent protection in one or more EPO member states, you can choose either to follow the national procedure in each state or to take the European route, which confers protection in all the contracting states in a single procedure.
If you want to patent your invention in one particular country only, it is advisable to file your application at the national patent office of the country concerned.
If you decide that you want a European patent, you have the choice between the direct European route and the Euro-PCT route. With the direct European route, the entire procedure is governed by the EPC alone. With the Euro-PCT route, the first phase of the grant procedure (the international phase) is subject to the PCT (Patent Cooperation Treaty), while the regional phase before the EPO as designated or elected Office is governed primarily by the EPC.
For further details see the European Patent Guide and the Euro-PCT Guide.