On = 1 = true
Off = 0 = false

NOT
A     NOT A
0     1
1     0

OR
A B   A OR B
0 0     0
0 1     1
1 0     1
1 1     1

AND
A B   A AND B
0 0     0
0 1     0
1 0     0
1 1     1

GATES implement logical functions
 for electronic circuits


A AND B AND C
= (A AND B) AND C

A B C   (A AND B)     (A AND B) AND C
0 0 0     0               0
0 0 1     0               0
0 1 0     0               0
0 1 1     0               0
1 0 0     0               0
1 0 1     0               0
1 1 0     1               0
1 1 1     1               1

Build a function/circuit from a truth 
  table
 
 A  B   F(A,B)
 0  0     0
 0  1     1  <- (NOT A) AND B
 1  0     1  <- A AND (NOT B)
 1  1     0

F(A, B) is true where either row 
  01 OR 10 are true

Row 01 is true when A=0 AND B=1
A=0 is true when NOT A is true
B=1 when B is true

F(A, B) = ((NOT A) AND B) OR (A AND (NOT B))