The visa is an authorization previously granted by a country so that a person from another country can enter and/or stay in the country that issues it. It is up to SEF to issue the visa, which must always be requested through Portuguese consulates or, in some cases, Portuguese embassies.
The visa to enter Portugal is, as a rule, mandatory, and can be waived only in certain cases (see exemption from visa for tourism, for example) or in some applications for residence permits (not in all). It is important to note that there is no so-called tourist visa. Tourists are exempt from visa.
Articles 45 and following of the Portuguese Foreigners Law (Law 23/2007) indicate the types of visas granted abroad, their scope and characteristics:
The reasons for cancelling a visa are provided for in Article 70 of the Foreigners Law (including staying outside Portugal for longer periods than authorized).
For more information about visa click here.
Can I extend my stay in Portugal?
Being a visa holder or benefiting from a visa exemption, it is possible to extend your stay in Portugal and / or other States that are part of the Schengen Area, as long as the conditions of admission are maintained and for up to one year, according to case. (Source: articles 71 and following of the Foreigners Law).
See more information about extending your stay in Portugal and necessary documents here.