This book is intended to serve as a compact manual of concepts and symbols used in critical thinking and formal logic. While most people believe that they can present a sound argument, or spot a faulty one, the majority are often unaware of the errors they make. This is particularly true when numbers or statistical evidence are involved. Logic is a valuable skill explicitly required in many pursuits including higher education, the sciences, law, engineering, security, medicine, information technology, and mathematics, to name a few. However it is often not formally taught in these fields. The aim of this book is to provide a basic but firm foundation in the concepts and symbols of formal reasoning for those who may want to take this study further, or who are pursuing studies or vocations that require logic, or who are just curious. To make learning easier, the notation used has been chosen to be consistent, symmetrical, intuitive, and widely used.