Habilitation is the procedure to achieve the highest university degree in many European countries in which the candidate fulfills certain criteria set by the university which require excellence in research, teaching, and further education. Its qualification (entitled often as "Privatdozent" or abbreviated as "PD Dr.") certifies the ability to be a "full professor" in these countries. This procedure also usually culminates with (after a positive evaluation of the Habilitation thesis) a scientific lecture with colloquium as well as a public inaugural lecture given by the applicant.
It is possible to get a professorship without habilitation, if the search committee attests the candidate to have qualifications equaling those of a habilitation and the higher-ranking bodies (the university's senate and the country's ministry of education) approve of that. However, while some subjects make liberal use of this (e.g., the natural sciences in order to employ candidates from countries with different systems and the arts to employ active artists), in other subjects it is rarely done.
Although disciplines and countries vary in the typical number of years for obtaining habilitation after getting a doctorate, it usually takes longer than for the American academic tenure. For example, in Poland until 2018, the statutory time for getting a habilitation (traditionally, although not obligatorily, relying on a book publication) is eight years. Theoretically, if an assistant professor does not succeed in obtaining habilitation in this time, they should be moved to a position of a lecturer, with a much higher teaching load and no research obligations, or even be dismissed. In practice, however, on many occasions schools extend the deadlines for habilitation for most scholars if they do not make it in time, and there is evidence that they are able to finish it in the near future.
In the Italian legal system, "habilitations" are different types of acts and authorizations.
(1) first a quantitative assessment, as each candidate for and ASN as associate or full professor must have at least 2 out of these 3 requirements: having published more papers than most associate or full professors in Italian universities, having received more citations than most associate or full professors in Italian universities, having an h-index higher than most associate or full professors in Italian universities;
(2) then, a specific committee (one for each scientific sub-field) will qualitatively evaluate the scientific CV of the candidates, considering funding, mobility, autonomy of the research, awards won, and so on.
The successful candidate will then receive his or her ASN habilitation as associate or full professor (or, in some instances, for both) and may thus apply for those vacancies in Italian universities.
The ASN habilitation is valid for 6 years, but a candidate can apply again to renew his or her habilitation 4 years after having received it. If an ASN habilitation application fails, the candidate can apply again, but only after a 12 months hiatus.
Due to extreme scarcity of tenure track positions in Italy, the ASN habilitation validity has been recently increased to 9 years through a government's decree in October 2019.
In the field of free regulated professions, protected by a professional body (architects, lawyers, engineers, doctors, pharmacists, journalists, etc.), it identifies the state examination, more properly called "state examination for the qualification for the exercise of professions" that allows the already graduated students or the ones having the necessary titles to register in the list of professionals and work. Many state exams include the possession of a specific qualification among the requirements. For example, to participate in the exam for the habilitation for the profession for an architect or an engineer, you must have already graduated from a university. However, in order to actually practice the profession it is necessary to register with the relevant professional association and, if the profession is exercised independently, it is necessary to have a VAT number. These exams are usually organized by the professional orders with the collaboration of the universities in the area.
In other cases, especially in the case of the health professions or of the childcare professional, not protected by a professional nature, the degree itself is a qualifying title.
Finally, some habilitations, since their activities can't be done autonomously, need to be hired in a suitable structure in order to effectively carry out the profession in question. This is for example the case of the education sector: once the qualifying examination has been passed, a public competition must be won for recruitment in an upper or lower secondary school.