What is "syntax"
Syntax is the set of rules that defines how the different symbols of a language (natural or programming) can combine validly.
Syntax rules define how characters combine to form "words" or tokens valid, and how these tokens combine in valid sequences with meaning (object of the semantics).
Syntactic source code analysis is the transformation of a linear sequence date of tokens in a hierarchical syntax tree (such as an AST, or Abstract syntax Tree). This process is called Parsing.
Use
Use this tag for questions about syntactic rules for a given programming language. Also include the tag corresponding to the language in question.