Expressions are groups of objects that can be combined into a single object. They typically involve literals, identifiers, and operators.

Whitespace (spaces and tabs) is generally ignored in expressions. Thus:
1  +  1, 
1 +1
all equal 2.
Expressions can be used in collections as well.
[1 + 1] => [2]

Expressions are a basic type of statement. Most statements contain a combination of keywords and expressions.