1. Requirements
   1. · Specification
   2. · Design
   3. Implementation
   4. Deployment
   5. · Maintenance
2. Methodologies
   1. Agile
   2. · Iterative
   3. RAD
   4. · RUP
   5. · Spiral
   6. Waterfall
   7. · XP
   8. · Lean
   9. Scrum
   10. · V-Model
   11. · TDD
3. Includ
   1. research
   2. new development
   3. prototyping
   4. modification
   5. reuse
   6. re-engineering
   7. maintenance
4. purposes
   1. meet the specific needs of a client
   2. fill a perceived need
   3. personal use