Korean individual celebrations
First 100 days partyIn the old days, many people died before they were born, or before their first 100 days of life. Therefore, someone who lived past the 100-day mark could be expected to live a full life. This day is more a "welcoming" day than a birthday and is now a tradition.
First-year partyLike the 100-day celebration. So many people died before their first year of life, so if they reached one year, they were most likely to continue to live a normal lifespan.
60th and 70th birthdaysSame as above. People who live to age 60, or especially 70, celebrate having such a long life.