Numerous beginning projects in "Getting Started with Arduino" have resistors, for example, in parallel after a button or photoresistor. What is the purpose of the resistor; please don't just say a pull-up or pull-down resistor (if that's the case), since I don't know what those are? Thanks...
It is a confusing thing to understand when you first come across it.
ladyada (Adafruit) has a good explanation of the why and how of pull-downs and pull-ups in one of her tutorials: Arduino Tutorial - Lesson 5.
I dont know if its just me.
But parts of the page have problems with Firefox .
White on white is so last year !!!