When you first encountered the colorful image on the cover of this book, you might have wondered what it represents? Is it the center of a sunflower? An aerial photograph of a thermal spring? A microscopic image of lake water? Perhaps you managed to recognize what is actually depicted: a magnified human eye.

Our eyes are fascinating structures that, through the coordinated action of millions of components, enable vision and subsequently perception of the surrounding world. Very often, what we see ignites our interest: What is it? How does it work? Why does it work this way? Almost all of us have an inherent curiosity about the natural world, which is one reason we take care of pets, grow plants, enjoy walks in nature, and visit zoos and aquariums.

This inherent curiosity lies at the heart of biology and is the inspiration behind this new handbook. The image on the cover was chosen because the book "Biology: Key Concepts" pertains to vision in the broadest sense – the goal is to see the big picture, to see the essence, to see how biology and our lives are connected.

This book will help you visualize the most important biological concepts – the core of each topic – and understand the relationships of these concepts to everyday issues that affect you and your loved ones. The text is accessible and accompanied by numerous images, inviting you to explore and understand the natural world. We hope that the book will enhance your interest in biology and that you will be able to see the world with new eyes.