Which is right?
I am always confused with the articles.
I hear that in arabic, there is no such thing as articles.
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.Sign up to join this community
Both sentences are correct: the grammatical construction is different and they have slightly different meanings.
He is expert in something.
No indefinite article (a/an) is present, so expert is an adjective that describes him. This sentence states that he has or shows a lot of knowledge or skill.
He is an expert in something.
In this sentence, an indefinite article (a/an) is present, so expert is a noun. The meaning is that he is a person who has or shows a lot of knowledge or skill.
The term an expert implies not only that he is good at something, but also that he is generally acknowledged to have this knowledge or skill.