A Midnight deadline is often specified for applications, submissions or contests in the Wikimedia community. This leads to numerous problems: What timezone is that for? Is it the beginning of the day or the end of a day? Is daylight savings a factor?
To accommodate the ambiguity of such a deadline, it is considered best practice to make the deadline for 23:59 Anywhere on Earth (AoE) as the last day to file (basically the last timezone on Earth). This means anyone who submits locally on the last day in their geography is accepted.
Projects and events are encouraged to use this as a best practice.