A commemoration is a ceremony that honors someone's memory. A commemoration can also honor an event, like a war.
A commemoration is a celebration of someone or something, usually in the form of a ceremony. Commemorations are often held on the anniversary of someone's birth or death. For example, there have been many commemorations for Martin Luther King to honor his contributions to the civil rights movement. On the anniversary of 9/11, commemorations are held to honor the dead. This word is all about remembering and respecting.