An anniversary is a date when people remember and celebrate what happened on the same date in a previous year. A married couple celebrate their anniversary on the date of their wedding. People also celebrate the anniversaries of important political events or of the founding of organizations.
1. We went to Hull for our anniversary.
2. … the sixty-sixth anniversary of the end of the First World War.
You do not use ‘anniversary’ to talk about the date when you were born. If you were born on January 1st, your birthday is on January 1st every year.
3. I always treat her to a gift on her birthday.
4. …soon after his ninetieth birthday in November 1964.