Inflammation aims at destroying invading pathogens (bacteria, viruses, etc.) and protects our body from infection. In order to achieve this goal, man has evolved an orchestrated response, the ultimate objective of which is to facilitate the emigration of leukocytes (white blood cells- the main players of the inflammatory response) from the bloodstream into peripheral tissue (skin, lungs, intestine, etc.), where most invading microorganisms penetrate the body and start replicating. This tutorial is meant to provide “non-experts” with a basic knowledge of this process. The tutorials include self-explanatory figures and legends, organized in a hypertext format, with simple explanations of the processes depicted. Legends can be visualized by passing the mouse over the numbered boxes. To facilitate comprehension, the various tutorials have been grouped based on the “magnification scale” used in the illustrations. Our unit of measurement is the leukocyte. A leukocyte can be imagined as a sphere with a diameter of approximately 10 microns. One micron is one thousandth of a millimeter, which is well below the minimum object size we can see by eye. Three magnification levels have been used: in the “tissue level” magnification, one centimeter equals 10 leukocyte diameters. In the “cellular level” magnification, one centimeter equals one leukocyte diameter. Finally, in the “molecular level” magnification, one centimeter equals one hundredth of a leukocyte diameter, an object size that only electron microscopes can visualize. We hope you will enjoy navigating these tutorials.