What amendments deals with the voting right of 18 years old?

The 26th Amendment to the United States Constitution specifically addresses the voting rights of citizens aged 18 and older. Ratified in 1971, it prohibits the denial or abridgment of the right to vote based on age for those who are 18 years or older. This amendment was a significant step in expanding democratic participation, particularly during the Vietnam War era when many young people argued that if they could be drafted for military service, they should also have the right to vote.