title: What is meant by the term "hook" in programming?
body: <p>I recently heard the term "hook" while talking to some people about a program I was writing.  I'm unsure exactly what this term implies although I inferred from the conversation that a hook is a type of function.  I searched for a definition but was unable to find a good answer.  Would someone be able to give me an idea of what this term generally means and perhaps a small example to illustrate the definition?</p>