Discovering the hidden messages in Apple's event invitations.

Apple is scheduled to hold an event soon.

Many fans are eagerly awaiting any clues about what new products or features may be in store. 

Comparing the invitations from the past 21 years with the products later unveiled at each event.

It seems that Apple frequently conceals hints while they are still visible.

Understanding what they mean, however, is more difficult. 

Apple employs a number of strategies to hint at upcoming releases that can be difficult to predict in advance.

The audience needs to learn how to follow the trail of breadcrumbs in order to make sense of the invitations.

Up until about 2013, Apple adopted a strategy that is best characterized as, well, blunt. 

In October 2001, Apple sent out invitations to guests and announced the arrival of a new product.