Date, Time, and Datetime

Date today = Date.today();
Datetime rightNow = Datetime.now();
Time noonish = Time.newInstance(12, 30, 0, 0);

Use Date when only the calendar day matters (a birthday, a due date). Use Datetime when the exact moment matters (when a record was created). Time alone is rare in business logic but exists for completeness.

Date enrollmentDate = Date.newInstance(2026, 2, 1);
Date courseEndDate = enrollmentDate.addMonths(4);
System.debug(courseEndDate); // 2026-06-01

A student enrollment system only cares about the day a course starts and ends — not the exact second — so Date, not Datetime, is the right fit here.

Dates support intuitive methods for moving forward or backward in time:

Date today = Date.today();
Date nextWeek = today.addDays(7);
Date lastMonth = today.addMonths(-1);

Under the hood this is just methods on the Date object — no manual "days in a month" math required, and it correctly handles month/year rollovers for you.

• Using Datetime when Date is what\'s meant. A Datetime carries time-zone-sensitive time information that can cause a date to appear to shift by a day depending on the viewer's time zone — a classic, hard-to-spot bug for anything that's genuinely just "a day," like a birthday.