Short answers, pulled from the story.
Substantial opposition to US involvement in the Vietnam War began in 1965, when demonstrations against the country's escalating role grew rapidly. The first large-scale protest, organized by Students for a Democratic Society, took place in Washington, D.C., on the 17th of April 1965, drawing more than 20,000 participants.
The National Moratorium demonstrations of the 15th of October 1969 drew approximately 15 million Americans in a single day, making them the largest single-day protests in US history to that point. A second round of Moratorium demonstrations on the 15th of November 1969 attracted even more, with over half a million rallying in Washington, D.C., alone.
African Americans opposed the war partly because the draft fell on them disproportionately: in 1965 and 1966 they accounted for 25 percent of combat deaths, more than twice their share of the population. In 1967-64 percent of eligible Black men were chosen for conscription compared to 31 percent of eligible white men. Martin Luther King Jr. gave a landmark anti-war speech at the Riverside Church in New York on the 4th of April 1967, connecting the war's cost to the neglect of civil rights and poverty at home.
More than 5,000 Vietnam War-related songs were recorded, spanning folk, rock, and classical music. Country Joe and the Fish released "I-Feel-Like-I'm-Fixin'-to-Die Rag" in October 1965, which became a movement anthem performed at Woodstock in 1969. John Lennon and Yoko Ono's "Give Peace a Chance" became widely recognized as the defining peace anthem of the 1970s.
Resistance to the draft took many forms, including public draft-card burnings beginning in May 1965 and organized card turn-ins that yielded more than 1,000 cards on a single day in October 1967. Over 30,000 people left the country for Canada, Sweden, or Mexico to avoid the draft, and by 1972 an estimated 200,000 to 500,000 people were refusing to pay excise taxes on their telephone bills as a form of war tax resistance.
On the 4th of May 1970, the Ohio National Guard opened fire on students demonstrating against the war at Kent State University, killing four students and wounding nine. The shootings triggered protests across the country and radicalized many more students nationally.