of this background knowledge has been somewhat forgotten over time, or has become a bit rusty, or even worse, completely obliterated by one's academic or professional specialization! This is why this book includes a couple of chapters on probability basics. Should such basics be crystal clear in the reader's mind, however, then these two chapters could be skipped at once. They can always be revisited later for backup, should some of the associated concepts and tools present any hurdles in the following chapters. This being stated, some expert readers may yet dare testing their knowledge by considering some of this chapter's (easy) problems, for starters. Finally, any parent or teacher might find the first chapter useful to introduce children and teens to probability. I have sought to make this review of probabilities basics as simple, informal, and practical as it could be. Just like the rest of this book, it is definitely not intended to be a math course, according to the canonic theorem-proof-lemma-example suite. There exist scores of rigorous books on probability theory at all levels, as well as many Internet sites providing elementary tutorials on the subject. But one will find there either too much or too little material to approach Information Theory, leading to potential discouragement. Here, I shall be content with only those elements and tools that are needed or are used in this book. I present them in an original and straightforward way, using fun examples. I have no concern to be rigorous and complete in the academic sense, but only to remain accurate and clear in all possible simplifications. With this approach, even a reader who has had little or no exposure to probability theory should also be able to enjoy the rest of this book. Events, event space, and probabilities As we experience it, reality can be viewed as made of different environments or situations in time and space, where a variety of possible events may take place. Consider dull and boring life events. Excluding future possibilities, basi