This text aims to bridge the gap between non-mathematical popular treatments and the distinctly mathematical publications that non- mathematicians find so difficult to penetrate. The author provides understandable derivations or explanations of many key concepts, such as Kolmogrov-Sinai entropy, dimensions, Fourier analysis, and Lyapunov exponents. Only basic algebra, trigonometry, geometry and statistics are assumed as background. The author focuses on the most important topics, very much with the general scientist in mind.