Blinking LED - Circuit explanation for a Newbie. [ANSWERED]

Greetings,

Arduino newbie here, awaiting my kit's arrival in the mail. In the meantime, I started looking over the SparkFun manual.

I'm a programmer, but an electronics newbie, and the manual has nice line-by line explanations of the sketch for each project, but the circuit is tripping me up:

|324x500

I hope someone would be willing to give me a complete newbie explanation of what's happening in the circuit. Specifically, I don't understand why a wire is needed from the 5V pin on the Arduino to the + row on the bread board? Isn't the current being sent (alternating) from Pin 13? This seems to me like current is coming to the breadboard from 2 different places.

Thank you kindly. I know this is utterly basic :blush: but got to start somewhere!

It's not necessary for that circuit - the 5v rail isn't connected to anything.

They probably show that for all the circuits, since you'd normally count on the + rail of the breadboard actually having a positive voltage on it.

Ohhh. So it's not needed?

I thought so. Thank you very much. Thought I was way more confused than I was. :)