と共に【とともに】

と共に means "together with" or "along with". It goes after a noun, or after the dictionary form of a verb. It belongs to writing, speeches and the news; in conversation, doing something with a person is といっしょに一緒に.

Changing along with something

When the noun is something that changes – age, the times, a process such as はってん発展 – と共に says that the second half changes with it.

For a gradual change like these, につれて says the same thing. につれて needs both halves to change step by step, though, so only と共に fits two things that happen at a single moment.

• × ベルが鳴るにつれて、観客が立ち上がった → ベルが鳴ると共に、観客が立ち上がった

"As well as"

After である, と共に says that something is one thing and another at once. The second half usually carries も.

A noun or a な-adjective needs である here; without it the noun reads as a companion: ×教師と共に、作家でもある. An い-adjective takes と共に directly.