Used alone

@ is the sigil for array variables

Operators containing this character

@@ array additional sigil for slice view
@() and @@() if empty, view of recent match result, otherwise array and array slice contextualizer functions a.k.a. coercers
\@ creates a "Capture from array contents"<>

When used inside regexes

<@ opens extensible metasyntax for matching on an list of rules

Special Variables

@= POD data as an array

As an adverb

:@ adverbial pair of array name and array data

Other Uses

@ in a Signature causes a method to expect an array object
*@ in a Signature creates a variable that absorbs all unnamed values
*@@ in a Signature performs multidimensional argument list binding
\c@ a NULL character in interpolated string context