共に

1. Origins, structure, and basic meaning

• Structure: 共に (ともに) can mean acting together with a person or changing in parallel with a development.
• Basic usage: A person walks a mountain trail with a friend; a city changes as its population grows.

2. Common pitfalls and similar expressions

• Human companionship and change progressing alongside a trend
  • 友人と共に names a fellow participant, while 増加と共に marks parallel development over time. Population growth is not a person accompanying the city.