What it means
と共に follows a noun to mean “together with” or “along with” and follows a dictionary-form verb to show that one change or event happens together with another. With verbs, it often describes a gradual or parallel change, similar to “as X happens, Y also happens.” This form is more formal and written than 一緒に, especially when expressing simultaneous change.
Usage note
と共に is relatively formal and is common in writing, speeches, announcements, and formal descriptions. In casual conversation, 一緒に is usually more natural for the meaning “together with,” while に伴って may be more suitable when emphasizing an accompanying change or consequence.
How to use it
研究者と共に、新しい薬を開発しました。
I developed a new medicine together with a researcher.
技術が進歩すると共に、生活も便利になりました。
As technology advanced, daily life also became more convenient.
研究者と共に、新しい薬を開発した。
I developed a new medicine together with a researcher.
技術が進歩すると共に、生活も便利になった。
As technology advanced, daily life also became more convenient.