This book describes some of the ways people write to each other, but it neither aims nor claims to cover more than a fraction of the whole field of writings. Indeed, writing is such a very large topic, and this is such a very small book, that the ideas which I have included really only provide a brief introduction to a few of its many aspects. In case it is not already obvious from the above, this little book is not written for experts. For those who are interested but not expert, I hope it will be very rewarding. Even for those who are expert but still interested, a quick browse may be worthwhile. However, if you are an expert and you are not interested in reviewing what you already know, then you have wasted quite enough time already.