Absentee voting (a.k.a "mail-in voting" and "by-mail voting") is conducted by mail-in paper ballot prior to the day of an election. Some states allow any registered voter to vote by absentee ballot (i.e. "no excuse absentee voting"). Other states require an excuse to vote by absentee ballot. Finally, some states require that absentee ballots be notarized or signed by a witness. In general, you can vote by absentee ballot if you will be able to vote in person on Election Day. If you're away at college, you can almost always vote by absentee ballot.
To be eligible to register to vote in the city, county or state in which you plan to vote absentee, you must meet some basic requirements: Be a citizen of the United States (Includes those persons born in Puerto Rico, Guam and the U.S. Virgin Islands). Be 18 years of age before the next election. Not be serving a jail sentence or be on parole for a felony conviction. Not be adjudged mentally incompetent by a court. Not claim the right to vote elsewhere. Be a resident of the local in which you will be voting
REGISTERING TO VOTE ABSENTEE
You'll find voter registration forms and absentee ballot applications for every state on LongDistanceVoter.org. This site includes voter registration forms, absentee ballot applications, deadlines, easy-to-follow-directions, and a breakdown of the relevant laws. Start there, and you'll have everything you need in just one place.Finally, you often need to know your county when registering to vote or applying for an absentee ballot. If you know your zip code, you can find your county on the U.S. Census Bureau's website.