Tributes serve to show admiration and respect for a person's life accomplishments. For example, famous musicians usually receive lifetime achievement awards followed by performances of their greatest hits as a tribute.
Tributes aren't limited to famous and influential individuals, and they are often used to show veneration to coworkers and teachers. In most schools, whenever a long-time teacher retires, her students bring her flowers and cards as a tribute for her years of service to the student body.
Tributes also occur when one country offers some kind of monetary payment to another country. Ancient civilizations often received tributes by lesser states as a sign of respect.