Methodology
Where the computed parts come from, and what they assume.
Moving holidays
Mother's Day is the second Sunday in May in the United States, the fourth Sunday of Lent in the United Kingdom and Ireland, and the tenth of May in Mexico. Father's Day is in June in most of the English-speaking world and the first Sunday of September in Australia and New Zealand.
We compute each of these from a rule rather than storing a date, and each rule records where it comes from: a statute where one exists, the church calendar where the date is a religious observance, and plain custom where the date is simply what people do. Easter, which the Lent dates depend on, is computed with the standard Gregorian method.
Anniversary materials
The traditional and modern material for each anniversary year is a convention, not a rule, and the lists that use them say so. Where the two traditions disagree we show both rather than choosing.
Reminders
Reminders are computed from the date you saved and sent at nine in the morning where you are. We take your time zone from your browser when you save a date, show it on your calendar page, and let you change it.
A date you recorded as a remembrance is treated differently: one quiet note on the day, and never a suggestion to buy something.
What we do not compute
We do not estimate delivery times, because we do not ship anything. We do not predict what you will want. Nothing on this site is chosen for you by a model.