Difference between "and" and "not"

[Hero192]

Hey guys, I am kinda confiused between the difference of

and 

and

not 

For example:

--Is this correct? When I have to use or and when I have to use and

function () 
    if source or isElement(source) then 
--code 
    end 
end 

[Mr_Moose]

All three words: or, and and not may be seen as logical gates. The first two are placed in between two statements that can be either true or false while not just negate whatever statement it's placed in front of. Consider the two lists below with 4 possible outcomes where 1 is true and 0 is false, last number is the result.

AND:

0 and 0 = 0

0 and 1 = 0

1 and 0 = 0

1 and 1 = 1

OR:

0 or 0 = 0

0 or 1 = 1

1 or 0 = 1

1 or 1 = 1

NOT:

not 0 = 1

not 1 = 0

So your example code would be considered as true if source is defined (could be anything except nil or false) or if source is an element. If you replace or with and however both the statements has to be true in order for the result to be true, ie. source must not be nil or false but source must also be an element, if source is not an element the result is false. Hopefully all this makes sense, it's all about basic logic.

[Hero192]

Thanks for your efforts to write down all that to let me understand, btw I got it

thanks alot I apreciate that !