Getting started with checking the digital and analog pins

Projects General Guidance
1

New to the UNO board, I run simple digitalRead to pins 0-9 and analogRead to pins A0-A5.
I expected to get 0 value for all pins because nothing is connected to the board but:

All digital pins return value 0 except pin (0) which gave value 1
All Analog pin return some value (around 350).

Why? No input is connected to the board. Why I am getting values?

Can someone explain it or link me with some explanation?

Thank you,

2

Floating inputs.

BTW, did you notice this

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3

TheMemberFormerlyKnownAsAWOL:
Is your name Dominic Cummings?

LOL

...R

4

aastrog:
All digital pins return value 0 except pin (0) which gave value 1
All Analog pin return some value (around 350).

Pin 0 is Serial Rx and is probably being held HIGH by the USB-TTL chip on the Uno board. Unless you need every I/O pin it is a good idea not to use pins 0 and 1.

When pins are not connected to anything (i.e. floating) they can produce random results because they need very little current to trigger them.

Note that the analog pins can also be used as digital pins - for example val = digitalRead(A0); is perfectly valid

...R