Agile is a philosophy defined by the Agile Manifesto (2001), written by 17 software thought leaders including Kent Beck, Martin Fowler, and Robert Martin. It’s not a single methodology — it’s a set of values that many frameworks implement differently.
The Four Values
| Instead of… | We value… |
|---|---|
| Processes and tools | Individuals and interactions |
| Comprehensive documentation | Working software |
| Contract negotiation | Customer collaboration |
| Following a plan | Responding to change |
The phrase after “instead of” isn’t unimportant — it’s just less important than the thing they value more.
The 12 Principles
Key ones for interviews:
- Highest priority: Satisfy the customer through early and continuous delivery of valuable software.
- Welcome changing requirements — even late in development.
- Deliver working software frequently — every couple weeks to every couple months.
- Business people and developers work together daily — no translation layer.
- Simplicity — maximizing the work NOT done — is essential.
- At regular intervals, the team reflects on how to become more effective — then tunes its behavior.
Agile vs Traditional
| Dimension | Traditional (Waterfall) | Agile |
|---|---|---|
| Requirements | Frozen early | Emergent |
| Team structure | Hierarchical, specialized | Cross-functional, self-organizing |
| Customer involvement | At milestones only | Continuous |
| Success measure | On budget, on scope | Customer value delivered |
| Documentation | Heavy | Just enough |
Q: Is Agile suitable for all projects?
A: No. Projects with fixed-price contracts, strict regulatory requirements, or distributed teams with timezone gaps can struggle with Agile. The “daily collaboration” principle is hard to maintain across 10 timezones.
Q: What does “responding to change over following a plan” mean in practice?
A: If the market shifts during the project, Agile teams pivot — they reprioritize the backlog and change direction. A Waterfall team would need to renegotiate the contract and rewrite the SRS, costing time and money.
Q: How does Agile handle documentation?
A: Agile says “just enough” documentation — what’s needed for maintenance, nothing more. Working software is the primary measure of progress. This can cause problems if the team under-documents and the original developers leave.
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