Citizens of EU, Switzerland, Liechtenstein and San Marino need an official identity card or passport (passport strongly recommended) to enter Finland.
Non-EU/EEA citizens must have a valid passport and will need to check at a local Finnish embassy or consulate whether a visa or a residence permit for Finland is required.
The residence permits in Finland are issued by the Finnish Immigration Service (Migri). We recommend you to start the application process as soon as possible. You should reserve at least two months, preferably more for the application process. Note, that you cannot arrive in Finland without the residence permit card in hand.
When you are granted a residence permit, your personal information will automatically be recorded in the Finnish Population Information System. You will be issued a Finnish personal identity code. If you cannot be registered in the Population Information System when you are issued with your residence permit (due to some local residence permit process, this is the case at least for citizens of India and Pakistan) you need to apply for the registration at the Digital and Population Data Services Agency after you have arrived in Finland (see "apply for a municiplaity of residence below").