Digital circuits can have many inputs and these are usually labelled with letters. Circuits can also have inputs that are permanently on (1,1) or off (0,0).
Boolean expressions are made up of variables and constants. Whilst an expression can include many variables, the value of each of these variables can only be a 0,0 or a 1,1.
A digital circuit can include many types of logic gate. However, these gates combine the fundamental functions of Boolean logic: AND, OR, and NOT. When you are asked to use Boolean algebra, you need only consider the operators and,∧, or,∨, and not,¬.
