∞ generated and posted on 2016.04.10 ∞

Means by which the body prevents the entrance of, identifies, and eliminates invasive organisms and cells.

The Immune System is the means by which a body protects itself from attack, either from within in terms of cancers and tumors or, in terms of pathogens and other infectious agents, from without.

The above video provides a good place to start towards appreciating the very basics of immunology.

The above video presents immunity in an approximation of its insane complexity.

The above video addresses the question, "What is Microbiology?", where a substantial aspect of immune systems exist to help organisms resist microorganisms.

The above video provides an introduction to blood and the immune system.