Daylight Saving Time bugs that shift appointments by an hour twice a year frustrate developers and users alike. The article explains why these glitches happen: ambiguous times when clocks fall back, missing hours when they spring forward, and the fact that different regions follow distinct rules that can change unexpectedly. It then walks through practical solutions for two popular languages.

In C#, the guide recommends using DateTimeOffset instead of plain DateTime, leveraging TimeZoneInfo for conversions, and explicitly handling ambiguous or invalid times with helper methods. For Python, the piece advocates timezone‑aware objects, the built‑in zoneinfo module, and the legacy pytz library for older versions. Both sections stress storing timestamps in UTC, keeping a separate timezone identifier, and avoiding server‑local time.

The article closes with real‑world examples of appointment schedulers and recurring events, and a checklist of common mistakes to avoid. By following these practices, teams can eliminate confusing time shifts, reduce support tickets, and deliver reliable scheduling across borders.