Give the function f the attribute HoldAll:

As a result, arguments are not evaluated prior to entering the (in this case nonexistent) function body:

Compare with a function g that has no attributes:

This is the full form of the evaluation result:

This is the full form of the input, before evaluation:

This is made possible by the fact that HoldForm has the HoldAll attribute:

Give the function inout the attribute HoldAll:

Define a function of two arguments that returns them wrapped in Hold as well as the first without wrapping:

Neither argument is evaluated prior to entering the function body, but the first argument is evaluated inside the function:

Many functions with scoping behavior have the HoldAll attribute:

Plotting lists of functions will use separate styling for the different functions:

If the list structure is not manifest, no separate styling is provided:

Use Evaluate to make the list structure manifest:

Different vector-valued functions in a list will still get separate styling:

Use HoldAll and Unevaluated to suppress evaluation of symbols wherever it would occur:

Find the length of a symbol's name even if it has a value:

Implement your own control structure:

Hold is a container with the attribute HoldAll:

Functions that operate on symbols often need the HoldAll attribute:

Without the attribute, they would operate on the symbol's value:

Control structures such as Table protect their arguments from evaluation:

Otherwise, global values might interfere with their operation:

Use Evaluate to force evaluation of an argument of a HoldAll function:

Force evaluation of the right-hand side of a delayed definition:

Use Unevaluated to temporarily treat a function as if it had the attribute HoldAll:

Suppress the evaluation of the arguments of a pure function:

Sequence splicing still happens for functions with the attribute HoldAll:

Unevaluated is stripped prior to entering the function body:

The attribute HoldAllComplete suppresses all three behaviors:

Substitution works inside a held expression:

Insert into a held expression:

NHoldAll protects arguments from N but evaluates them normally otherwise:

HoldPattern protects patterns from evaluation but does not interfere with pattern matching: