Welcome to Terrapin Logo. Logo is a general purpose programming language that is powerful, yet easy to use. Logo's simplicity makes it especially appropriate for beginners of all ages, yet it is also a tool for learning and exploring.

Like many computer languages, Logo provides you with the capability to create attractive graphic images, perform calculations, maintain and update data, and even create sounds and play music. Logo, however, was designed to make doing these tasks easy and fun and their mastery within the range of those with little or no computer training.

Logo is different from other languages in several ways:

Logo is responsive. You give Logo a command and Logo responds immediately and often dramatically.

Logo is intuitive. The purpose and effect of Logo commands are easily understandable from their names. Their structure and syntax are similar to conversation.

Logo is procedural. You begin by learning some of the words that form Logo's vocabulary. Then you explore how these words enable you to draw designs on the computer screen with the Logo turtle. As you progress, you learn to add new words to Logo's vocabulary by naming and writing your own procedures. These new commands can in turn be used in naming and defining even more new commands, all of which become an integral part of Logo. In this way, you extend the power of Logo according to your own ideas and discoveries.

Terrapin Logo, the latest implementation of Logo, maintains the ease of use of the Logo language while greatly extending its capabilities. This manual is designed as a tutorial in how to use Terrapin Logo and to explore its features. You can go through it sequentially or jump from chapter to chapter as a topic interests you. Enjoy exploring with Logo!

Stan Munson is a computer programmer and technical writer with experience in industry, banking, and education. Exploring with Logo has been one of Stan's favorite hobbies along with reading the works of Charles Dickens and the Brother Cadfael Chronicles of Ellis Peters. Stan lives in upstate New York with his two children and his high school sweetheart wife to whom this book is dedicated.