This book is suitable to be used as a textbook in an educational institution or training centre where introductory computer courses are offered. It assumes no previous knowledge of the subject and uses very simple language and illustrations to explain the key terms. The book has both theory and practical. It discusses software piracy, spreadsheets, communication and networking, Internet and e-mail, social and economic implications of computer usag, and computer programming (designing algorithms). Computer viruses are discussed under social and economic implications, where causes and prevention measures are given. Using a spreadsheet is demonstrated using Microsoft Excel 2010, do not forget that hands-on is the best teacher. Algorithm is a step in computer programming. Once you understand how you logically solve a problem then you are a potential Software Engineer. This book is for grade 9 learners and the grade 8 learners' book is also available. You can also consider Success in Computer Studies series (Level 1, Level 2 and Level 3). These books can also help especially if you are using Windows 7 and Microsoft Office 2007.