In the US, there are certain ways one can vote.
The first way is to have an absentee ballot. If you will be absent (out of the US during the voting cycle), you can request a mail-in voting ballet, which will be mailed in prior to the general election, and counted on the same time. This is typically for people that are in the military or are out of town.
The second way to vote is to vote in person in a voting booth. Voting booths are designated by the government, and places can apply to be able to accept voting ballots. One simply has to go to a designated voting area and fill out the ballot and submit it in that place.
The way that someone votes is simple. One is given a ballot, and it is broken down into government offices and underneath is listed the candidates. The candidates by themselves have their party alignments listed with their name, usually (D) for Democrat, (R) for Republican, and (I) for Independent. One simply fills out the form and then puts it into a ballot box, which would be submitted. The same is for mail-in. One fills out their ballot, and submit it through the mail, which would make it's way to be counted, though you will have to submit early.
As for mail, there has lately been questions on the validity of it. California in especially almost forces people to use mail-in, which has a high probability of voter fraud. Already in the news we see thousands of early-voter ballots being dumped instead of being turned in, which could lead to one party getting a edge over another based on those few hundred votes.
Essentially, you can vote in person, with an absentee ballot, or by mail.
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