We humans simply love the idea of preservation. The most common example of this is a refrigerator. Although a refrigerator does serve many other purposes, we love them because they allow us to stash all the goodies that we can get our hands on and then gobble them later. Nothing works better than a refrigerator!
However, when we are dealing with more sensitive materials, such as medicines and drugs, the presence or absence of preservation could mean life or death for people, so we need to be extra careful that materials are not spoiled before they are used. The question is, how do we make that happen?