Events are normally sorted by their start date and time. In the Timeline view events starting before another will always be shown above events that start later. But there are times when you have a list of events all with the same start date, time and resource but wish to view them in a certain order.
You can use the events Priority setting so High priority events are shown above lower priority events. The Priority setting can be set in the event, but you can also just drag events above or below others to change their priority, and thus their order, by using simple drag and drop.