FullForm of a typeset expression:

FullForm of a graphic:

The FullForm will show the precedence of operators:

Grouping with parentheses affects the precedence:

See the underlying interpretation for a TraditionalForm output:

Perform replacements:

Replace lists with a new wrapper newhead:

Multiplications have the head Times:

Find all multiplications in expr:

See the underlying expressions:

The typeset form of FullForm[expr] is interpreted the same as expr when used in input:

Copy the output and paste it into an input cell. The Power[x,2] is interpreted as x²:

When an input evaluates to FullForm[expr], FullForm does not appear in the output:

Out is assigned the value x², not FullForm[x^2]:

FullForm has linear formatting without special syntax:

InputForm formats as linear input:

TreeForm graphically displays an expression's tree structure:

Even when an output omits FullForm from the top level, it is not stripped from subexpressions:

The output does not have FullForm in it:

However, the variable e does have FullForm in it, which may affect subsequent evaluations:

The product is not evaluated due to the intervening FullForm:

Assign variables first and then apply FullForm to the result to maintain computability:

Pattern matching is based on the FullForm:

The previous fraction is represented as a single Power expression:

Perform the desired replacement: