Learn Hardcore Korean: naneun hyudaeponeuro jaju sajineul jjigeo.

는 is the topic marker. It highlights 나 (“I”) as the topic or context of the sentence—“as for me.” If you used 나 + 가 (내가), you’d be simply stating “I” as the subject without that nuance of “speaking about myself.”

What role does 으로 play in 휴대폰으로? Why not just 로?

으로 is the instrumental particle meaning “by/with.” It marks the tool or means used to perform the action. You choose 으로 (not 로) after a noun ending in a consonant (휴대폰 ends in ㄴ). After a vowel-final noun you would use 로.

What part of speech is 자주, and where does it go in a Korean sentence?

자주 is an adverb meaning “often.” Adverbs in Korean usually appear before the verb they modify. Here it sits between the instrument phrase (휴대폰으로) and the object (사진을), but you could also say 나는 사진을 자주 찍어 or 나는 자주 사진을 찍어—Korean word order is fairly flexible as long as the verb comes last.

Why is the verb ending 찍어 instead of the polite 찍어요?

찍어 is the informal (반말) present-tense form of 찍다. It’s used among close friends or when you’re speaking casually. To make it polite (해요 체), you would say 나는 휴대폰으로 자주 사진을 찍어요.

What’s the dictionary form of 찍어, and is 찍다 irregular?

The dictionary (infinitive) form is 찍다 (“to take [a photo]”). It’s a regular verb: you simply drop -다 for most conjugations and add the appropriate ending.

Can 나는 be omitted?

Yes. Korean often drops the topic or subject when it’s clear from context. You can just say 휴대폰으로 자주 사진을 찍어 if “I” is understood from the conversation.

Why is 사진 marked with 을?

을 is the object marker for a consonant-final noun (사진 ends in ㄴ). It shows that 사진 is the direct object of the verb 찍어. If the noun ended in a vowel, you’d use 를 instead.