Project 02 Digital Out voltage

Hardware The Arduino Starter Kit
1

Hi

I'm loving my Arduino Starter Kit. I'm a total electronics noob so go easy on me :wink:
I've been going back and reviewing the first 4 projects and I just want to check my understanding of something.
When you use a digital output pin from the Arduino, and turn it "HIGH" using code, the voltage provided by the digital output pin is nothing to do with the initial 5V power connection from the Arduino.
Is that correct ?
If so, is the voltage provided by the digital output pin also 5V ?

Or am I totally wrong and the initial 5V current is the same 5V that is initially provided by the board ?

The reason that I want to know this is because I am trying to understand how the green LED in Project 02 is powered when the switch is "OPEN"

Did this make any sense to people or am I just gibbering ?

Project circuit diagram attached

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2

Please ignore this - I believe I have answered my own question now.

3

Because you love it so get a digital multimeter and measure the high output...its less than 5 and low is greater than zero due to internal construction of the semiconductor material we call them TTL levels.