A brief explanation of some of the Korean particles. Particles are suffixes that immediately follow nouns or pronouns.

은/는: topic

Marks the topic of the conversation.

나는 학생이다.
I am a student.

이것은 연필이다.
This is a pencil.

이/가: subject

Marks the subject of the sentence.

내가 마셨다.
I drank.

저것이 한강이야.
This is the Han river.

은/는 vs. 이/가

The subject and the topic particles seem fairly similar. Here are the main things to note:

• 은/는 signifies an introduction of a topic
• 은/는 can be used to make a general statement
• 이/가 identifies the subject of the discussion
• 이/가 specifies a particular subject

을/를: object

Specifies the object of the sentence. You can have multiple object markers in a sentence.

나는 라면을 먹었다.
I ate ramen.

에: location, time

Used for showing where something is located at, or where someone/something is going to. It is also used for time.

그는 가게에 있다.
He is at the store.

마이클은 8월에 왔다.
Michael came in August.

도/또한: additive

Means "also" or "too." 또한 is used when you want to talk about multiple qualities of the same subject.

그녀도 공부한다.
She studies too.

정남은 군인이었다. 그는 또한 정치가였다.
Jeong-nam was a soldier. He was also a politician.

Sources include /r/Korean, Wikipedia, and LP's Korean Language Learning blog.