Liberty Bonds were government-issued securities sold to help finance the United States' involvement in World War I. Introduced in 1917, these bonds encouraged citizens to support the war effort by lending money to the government, which promised to pay back the principal with interest after a set period. The sale of Liberty Bonds was a significant part of the war financing strategy, raising over $17 billion. They were marketed through patriotic campaigns, appealing to Americans' sense of duty and national pride, making them a symbol of support for the troops and the nation during a critical time.