The query "when is" is incomplete and lacks context, but from the search results it is often associated with questions about dates or times for events such as holidays (e.g., "When is Easter?"). For example, Easter falls on a Sunday between March 22 and April 25, with the specific date changing each year based on a lunar calendar calculation. Other common "when is" questions involve dates of public holidays or specific events. If there is a particular event or subject for which the timing is needed, please specify so more precise information can be provided.