Concurrent Models (Concurrent Engineering): Activities exist concurrently in different states.

Event-driven transitions between states for activities (e.g., "under development," "awaiting changes").
Applicable to all types of development, provides accurate project state.

Component-Based Development (CBD): Constructs applications from prepackaged software components (COTS).
- Steps: Research components, consider integration, design architecture, integrate, test.
- Promotes reuse, reduces cycle time and cost.
Formal Methods Model: Mathematically based techniques for specification, development, and verification.
- Aims for defect-free software, eliminates ambiguity/inconsistency early.
- Weaknesses: Time-consuming/expensive, requires specialized skills, difficult communication with non-technical stakeholders.
- Used for safety-critical software.
Aspect-Oriented Software Development (AOSD): Addresses "crosscutting concerns" (properties spanning multiple functions/features).
- Aims to localize crosscutting concerns into "aspects" for better modularity.
- Process likely combines evolutionary and concurrent models.

Ability to respond appropriately to change.
Emphasizes rapid delivery of operational software, customer collaboration, team autonomy.
Adapts incrementally to project and technical conditions.

Most widely used agile approach.
Values: Communication, simplicity, feedback, courage, respect.
Process:
- Planning: User stories (customer-written, prioritized), project velocity (stories/release).
- Design: KIS (keep it simple), CRC cards, spike solutions (prototypes), refactoring (improves internal structure without altering external behavior).
- Coding: Unit tests before coding, pair programming (real-time problem solving & QA), continuous integration.
- Testing: Automated unit tests, acceptance tests (customer-specified, based on user stories).
Industrial XP (IXP): Refines XP for large organizations.
- Adds: Readiness assessment, project community, project chartering, test-driven management, retrospectives, continuous learning.

Adaptive Software Development (ASD): Focuses on human collaboration, self-organization.
- Phases: