Syntax in linguistics refers to the arrangement of words and phrases. Syntax covers topics like word order and grammar rules, such as subject-verb agreement or the correct placement of direct and indirect objects. 

Syntax is essential to understanding constituency, the term for multiple words acting as a single unit. In long and complex sentences, constituency is necessary to determine the hierarchy within the sentence, particularly with sentence diagramming. 

Syntax, on the other hand, is about the arrangement or order of the words. There’s less choice involved, and there are more restrictions based on grammar rules. 

Syntax also affects style, in particular, sentence structure and sentence length. Just like some authors are known for using simple or elaborate words, some authors are known for using simple or elaborate sentences. Furthermore, in sentences with multiple clauses, authors can choose which clauses come first and which come last, influencing how the reader interprets them.