Compulsory voting
Countries that have compulsory voting by law but do not enforce it:Although voting in a country may be compulsory, penalties for failing to vote are not always strictly enforced. In Australia and Brazil, providing a legitimate reason for not voting (such as illness) is accepted. In Argentina, those who were ill on voting day are excused by requesting a doctor to prove their condition; those over away from their voting place are also excused by asking for a certificate at a police station near where they are. Belgian voters can vote in an embassy if they are abroad or can empower another voter to cast the vote in their name; the voter must give a "permission to vote" and carry a copy of the eID card and their own on the actual elections.
Voter registration
Voter registration (or enrollment) is the requirement that a person otherwise eligible to vote register (or enroll) on an electoral roll before they will be entitled or permitted to vote. Such enrollment may be automatic or may require application being made by the eligible voter. The rules governing registration vary between jurisdictions. Some jurisdictions have "election day registration" and others do not require registration, or may require production of evidence of entitlement to vote at time of voting. In some jurisdictions registration by those of voting age is compulsory, while in most it is optional. In jurisdictions where registration is voluntary, an effort may be made to encourage persons otherwise eligible to vote to register, in what is called as a voter registration drive.