The priority date is the first date upon which an application for initial protection, which determines the authority of an invention or industrial property rights, is presented, as of which exclusivity rights would be obtained in the event of the protection sought being granted. For the next twelve months after the priority date (in the case of patents and utility models) or for the next six months after the priority date (in the case of industrial models and trademarks), by virtue of the Paris Union Convention, all countries recognise said priority date, no matter the country in which the initial protection application was presented. As such, they accept the extension of the protection applied for and recognised in their own territory, as the filing date, the date of the initial priority provided that the text to be extended has not been modified beyond a simple literal translation.

This means that, during the first year an application is in force, it is possible to apply for protection in any other country in the world as well, conserving the date of the first application. Once this twelve-month period has expired, this possibility comes to an end and as such, the invention described in the application passes into the public domain of all those countries in which the extension has not been applied for as of the date the application was published or since the object protected was revealed.