Date/Time component of WordPress core dates back to ancient PHP 4 times. As result work with dates, times, and timezones is full of pitfalls. Trivial actions in admin and code can lead to massive errors in output of time information. Errors that will confuse both people and software. The talk will summarize years of experience with bugs and edge cases in Date/Time component: 1. Point out the most common (and trivial to make!) errors. 2. Provide practical solutions for robust development and output practices. 3. Cover the work being done in core on resolving the outstanding issues and direction towards better functionality.