When you register, you are asked if you want to join a political party. A political party is a group of people who share the same views about how the government should be run and what it should do. They pick candidates to run for office.
Party members work together to win elections and change laws.
It does not cost anything to join a party. You do not have to do anything for the party. If you like, you can help them with their campaigns . If you do not choose a party, you can not help choose party candidates in the primary for the Fall election.