First, I acknowledge that there are several questions regarding this topic in the forum, however, the answers assume too much background knowledge of electronics to be of use to a true beginner (like myself). That being said, if you choose to answer, please limit your responses to heuristic (non-technical) explanations.
My understanding of a pull-up resistor, is to ensure a consistent charge on a line, as opposed to a disconnected line, which could potentially fall victim to electrical fields and then produce noise. The noise could then be interpreted as an input signal and cause unexpected results from your device.
Question 1) Am I correct in my understanding of the purpose of pull-up and pull-down resistors?
Question 2) How does this work? Can someone provide a metaphor or analogy to describe what exactly is taking place with the electrical current?