5 Lexical conventions [lex]

5.6 Tokens [lex.token]

1
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There are five kinds of tokens: identifiers, keywords, literals,11 operators, and other separators.
Blanks, horizontal and vertical tabs, newlines, formfeeds, and comments (collectively, “whitespace”), as described below, are ignored except as they serve to separate tokens.
[Note 1: 
Some whitespace is required to separate otherwise adjacent identifiers, keywords, numeric literals, and alternative tokens containing alphabetic characters.
— end note]
11)11)
Literals include strings and character and numeric literals.