And that's how we develop something called active immunity. So vaccines are normally developed in laboratories by many different methods that we're not going to focus on in this lecture. Typically, the pathogen is inoculated which means that it is changed in some way or form as to ensure that not too much damage is actually taken by the body so that we don't feel the same exact bad effect that we would normally feel in the natural process of infection. And in many cases, receiving a vaccine essentially creates no effects whatsoever no effects that we can actually visibly see or physically feel. Now, to further prevent us from actually experiencing any form of discomfort during vaccination what medical researchers do is they essentially kill off that pathogen altogether and they only take a very small portion of an antigen of that pathogen. So they essentially cut that pathogen and use only the epitote, the antigenic determinant of that antigen because it's that part of the antigen that ultimately binds to the antibodies of our body.