Habilitation is a term used within the university system in Germany, Austria, and some other European countries. It can be used to describe either a qualification, the process of earning that qualification, or the dissertation written as part of that process.
In order to hold the rank of Professor within the German system, it is necessary to have passed the Habilitation. It is thus a qualification at a higher level than the Ph.D, and it is usually earned after several years of working as a Privatdozent within a university. The Habilitation is usually awarded after a public lecture expounding the substance of the dissertation. Those who have achieved Habilitation sometimes denote the fact by placing the abbreviation "Dr. hab." or "Dr. habil." before their names, though this is not common.
The degree of Docteur d'Etat formerly awarded by universities in France had a somewhat similar purpose.
Although these awards are at a higher level than the PhD, they should not be equated to the higher doctorates awarded by universities in the United Kingdom, the United States and the Commonwealth: these are given in recognition of an extended research career, and would normally only come after some years at professorial status.