Robert C. Martin says that Agile is a small idea about the small problem of small programming teams doing small things.
Agile is not a big idea about the big problem of big programming teams doing big things.
Big things don’t get done by big teams; big things get done by the collaboration of many small teams doing many small things.
To help popularize this, back in the early 2000s, the idea was given a name. “Agile.”