Twelfth grade, Senior year, or Grade 12 are the North American names for the final year of secondary school. In other regions it is also equivalently referred as Class 12 or Year 12. In most countries students then graduate at age 17–18. Some countries have a thirteenth grade, while other countries do not have a 12th grade/year at all. Twelfth grade is typically the last year of high school.Graduation Year