How does punctuation affect syntax?
Syntax is defined as an arrangement of words that complete a fluent, proper sentence; for example, all the punctuation I used in this sentence has well-shaped syntax.
Usually, common syntax follows the subject-verb agreement; however, we see that most writers like to stretch their grammatical restraints and go beyond the rules of common syntax. When an author negates the subject-verb agreement, it's still syntax. It's not a complete sentence, but repeated punctuation in a poem, for instance, can create an idea of the sentence.
"To Autumn" by John Keats
#"To swell the gourd, and plump the hazel shells"#
#color(white)(" ")"With a sweet kernel; to set budding more,"#
#"And still more, later flowers for the bees,"#
#"Until they think warm days will never cease,"#
#color(white)(" ")"For summer has o'er-brimm'd their clammy cells. "#
In this example, we see commas, semicolons, and apostrophes stepping in to give the poem personality. The way we say it out loud will be influenced by these punctuation marks.