は・
Choosing the topic or subject marker
Choose by the job you want the marked phrase to do. は sets the frame—what you are talking about—or contrasts one choice with another. が points out who or what acts, exists, or has the quality being described. It also marks the target in certain learned expressions of preference, skill, and understanding. Because these jobs are different, both particles can appear naturally in one sentence.
Start with what you are trying to do
Set an established topic
は
The person, thing, time, or place is identifiable, and you want to make a statement about it.
Identify who or what
が
The subject is new, newly noticed, unknown in a question, or the answer that identifies the unknown subject.
Contrast alternatives
は
You are separating one choice from another or limiting your claim to one choice.
A real alternative must be stated or clear from the context.
Mark a learned feeling or ability target
が
The noun is the target of an established expression such as 好き, 嫌い, 上手, or わかる.
This is not a general replacement for the object marker.
Unknown first, established afterward
誰が受付を担当しますか。
Who will handle reception?
Analyze佐々木さんが担当します。
Ms. Sasaki will.
Analyze佐々木さんは八時に来ます。
Ms. Sasaki will come at eight.
AnalyzeThe question and direct answer use が because they ask for and identify the unknown person. Once that person is established, は can make her the topic of the next statement.
The same marker, two jobs
A speaker describes the same café in two different contexts.
この喫茶店は静かですが、隣の店はにぎやかです。
This café is quiet, but the place next door is lively.
AnalyzeThe two places are explicitly set against each other.
Takeaway: The written form alone does not tell you whether は is neutral or contrastive. Look for a relevant alternative in the sentence or conversation.
Two markers, two jobs
A phrase marked by は can provide the larger frame while another phrase marked by が does a more specific job inside the statement.
この写真は兄が撮りました。
My older brother took this photograph.
AnalyzeLiterally: As for this photograph, my older brother took it.
The photograph is the topic; the older brother is identified as the person who took it.
私は韓国料理が好きです。
I like Korean food.
AnalyzeThe speaker supplies the viewpoint, and Korean food is the target of the preference.
Learn the whole expression
One speaker talks about the same school subject in two different sentence patterns.
Takeaway: English uses an object after both “like” and “study,” but Japanese does not copy that pattern mechanically. Learn が好き as one established combination; an ordinary action verb may instead take を.
Natural in speech and writing
These uses are neutral and fundamental in both conversation and writing. In conversation, speakers often leave out an already obvious topic or subject, so do not add an explicit noun and particle merely because English states one. When a phrase is present, interpret it from the surrounding context: は may be neutral or contrastive, and が may identify a subject or belong to a learned feeling or ability pattern.
More examples across the family
田中さんは図書館で働いています。
Mr. Tanaka works at a library.
Analyze外で犬が鳴いています。
A dog is barking outside.
Analyze紅茶は飲みますが、コーヒーは飲みません。
I drink tea, but I do not drink coffee.
Analyze母は辛い料理が嫌いです。
My mother dislikes spicy food.
Analyzeこの絵は学生が描きました。
A student painted this picture.
AnalyzeLiterally: As for this picture, a student painted it.
どの席が空いていますか。
Which seat is available?
Analyze