In this essential, Alexander Knochel provides an overview of current issues and open questions in particle physics and cosmology, explaining how the Large Hadron Collider can contribute to their clarification. The author takes the reader on a journey through new physical phenomena, the limits of our existing theories, and theoretical considerations about what we might expect at these energy scales that have not yet been reached in the laboratory. It is exciting, as the world's most powerful particle accelerator, the Large Hadron Collider, is back up and running at record energy levels.