Apostrophes:
* Show possession: "The cat's tail" (the tail belonging to the cat)
* Form contractions: "I'm" (I am), "don't" (do not)
* Mark pluralization of letters and numbers: "mind your p's and q's," "the 1980s"
Hyphens:
* Combine words: "well-being," "mother-in-law"
* Prevent ambiguity: "re-cover" (cover again) vs. "recover" (get better)
* Attach prefixes: "pre-existing," "non-profit"
* Create compound adjectives: "state-of-the-art," "high-pressure"
Without apostrophes and hyphens:
* Writing would be confusing and ambiguous.
* Sentences would be harder to read and understand.
* Grammatical rules would be harder to follow.
Therefore, these punctuation marks are essential for clarity and proper grammar in English writing.