<P> As of the 2016 Games in Rio de Janeiro, all of the current 206 NOCs and 19 obsolete NOCs have participated in at least one edition of the Summer Olympics . Competitors from Australia, France, Great Britain, Greece, and Switzerland have competed in all twenty - eight Summer Olympic Games . Athletes competing under the Olympic flag, Mixed Teams and the Refugee Team have between them competed at six Games . </P> <P> 119 NOCs (110 of the current 206 NOCs and 9 obsolete NOCs) have participated in at least one Winter Games, and athletes from fournteen nations (Austria, Canada, Czech Republic, Finland, France, Great Britain, Hungary, Italy, Norway, Poland, Slovakia, Sweden, Switzerland, and the United States) have participated in all twenty - three Winter Games to date . </P> <P> The host city for an Olympic Games is usually chosen seven to eight years ahead of their celebration . The process of selection is carried out in two phases that span a two - year period . The prospective host city applies to its country's National Olympic Committee; if more than one city from the same country submits a proposal to its NOC, the national committee typically holds an internal selection, since only one city per NOC can be presented to the International Olympic Committee for consideration . Once the deadline for submission of proposals by the NOCs is reached, the first phase (Application) begins with the applicant cities asked to complete a questionnaire regarding several key criteria related to the organisation of the Olympic Games . In this form, the applicants must give assurances that they will comply with the Olympic Charter and with any other regulations established by the IOC Executive Committee . The evaluation of the filled questionnaires by a specialised group provides the IOC with an overview of each applicant's project and their potential to host the Games . On the basis of this technical evaluation, the IOC Executive Board selects the applicants that will proceed to the candidature stage . </P> <P> Once the candidate cities are selected, they must submit to the IOC a bigger and more detailed presentation of their project as part of a candidature file . Each city is thoroughly analysed by an evaluation commission . This commission will also visit the candidate cities, interviewing local officials and inspecting prospective venue sites, and submit a report on its findings one month prior to the IOC's final decision . During the interview process the candidate city must also guarantee that it will be able to fund the Games . After the work of the evaluation commission, a list of candidates is presented to the General Session of the IOC, which must assemble in a country that does not have a candidate city in the running . The IOC members gathered in the Session have the final vote on the host city . Once elected, the host city bid committee (together with the NOC of the respective country) signs a Host City Contract with the IOC, officially becoming an Olympic host nation and host city . </P>

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