1. Present simple tense: Used throughout the answer (e.g., "Most people really enjoy taking photos..."), which is appropriate for general statements and habits.
2. Relative clause: "such as birthdays, weddings, or big festivals" adds detail and examples to clarify the main idea.
3. Infinitive of purpose: "to freeze those moments in time" clearly explains the reason for taking photos, showing a good use of purpose clauses.
4. Not only... but also structure: "remember not just what happened, but also the mood and excitement of the day" is a nice way to add emphasis and show a more advanced grammatical structure.