An administrative act is a voluntary statement made in the exercise of public service and generates immediate individual legal effects. This type of Act is a manifestation of the administrative authority which applies unilaterally and imperatively.
The fact of being a declaration, the physical acts of the public administration are not part of its administrative acts. Moreover, the administrative acts are Executive because they did not need the authorization of the judicial power to impose their conditions and require that they are respected.
An administrative act may be classified according to its origin, its contents, its form, its effects, its recipients or its link with a pre-existing norm.
According to their origin, acts can be simple (when they come from a single body) or complex (if they are at the origin of two or more organizations). The content, for its part, determines whether the administrative act is constitutive (creates, modifies or exterminate legal relationships) or declarative (when it certifies a legal situation).
On the form, the Act can be express (when it occurs formally) or presumed (when it is manifested from the administrative silence during a period of time). Compared with the effects, it is possible to tell the difference between positive acts (those that generate a new legal situation) and acts unfavourable (those that restrict legal heritage).
Then the classification from recipients generates unusual character acts (addressed to a single person) or of a general nature (addressed to all indeterminate set). Regarding their relationship with a prior norm, acts can be set (the administration applies a standard that determines the content of the Act) or not resolved (when it is possible to choose among several solutions).