In the case of a national registration (which can also be regional, such as for the Benelux or the European Union) the trademark is filed directly with the local trademark authority of that country, often with the help of a local agent. In the case of an 'International Registration', your trademark is applied for through the International Registration System via the 'registration' body WIPO. You can then extend your trademark to several countries with one application and it is also easier to change data or add countries. WIPO forwards the applications to the local authorities, who will then check and register the trademark in accordance with the local rules.