Definition
Agile is an approach to software development that delivers work in small, frequent increments rather than one large release.
Why It Matters
Agile matters because requirements change. Projects planned entirely upfront assume perfect knowledge at the start. Agile accepts uncertainty and builds in regular adjustment opportunities.
Example
A business commissions a client portal. After sprint one they see a login and project list. They realise they need a request form more urgently than reporting. The team reprioritises — delivering what the business actually needs most.