Used for the origin or source of something, often in a cultural, historical, or personal sense. Common in phrases like ルーツを探る (to explore one's roots).
He visited his ancestors' hometown to explore his roots.
The roots of this music are in Africa.
He visited his ancestors' hometown to explore his family's roots.
This dance has its roots in Africa.
She went on a trip to trace back her immigrant grandparents' roots.
ルーツ is a loanword used mainly for personal, family, or cultural origins, whereas 根 is the native word that also covers literal plant roots and abstract root causes.
ルーツ is a casual, often personal word for one's roots or ancestry, while 源流 is more formal and used for traditions, cultures, or rivers.
ルート (route) and ルーツ (roots, as in ancestry or origin) sound similar but mean completely different things.
Loanword from English 'roots'.