He is a specialist in that field.

He has expert knowledge.

He is studying computer science at a specialized school.

He couldn't say anything about issues outside of his field of expertise.

There are many different specialty stores in this town.

That stupid man, he was late again.

It's important to believe in yourself.

She uploaded a selfie to Instagram.

She took a selfie and uploaded the photo to social media.

He likes talking about himself and often talks about his experiences and thoughts.