The system boundary separates what you build from its environment; the context boundary separates the relevant environment from the irrelevant rest of the world.

* Two nested boundaries — the system boundary divides the system from its context; the context boundary divides the relevant context from the irrelevant environment. *

• System Boundary: Determines which aspects pertain to the system to be developed and which belong in the system context
• Context Boundary: Determines which aspects pertain to the system context and which are part of the irrelevant environment

Example: For an e-commerce website:

• Inside system boundary: Shopping cart, checkout, product catalog
• In system context: Payment gateway, shipping provider, customer
• Irrelevant environment: Competitor websites, unrelated government regulations

Elicitation, Documentation, Validation and negotiation, and Management — grouped into two main blocks (everything under Elicitation, plus the cross-cutting Management).

* The four RE activities — Elicitation, Documentation, Validation & negotiation, plus the cross-cutting Management. *

The standard names four core activities, but they sit in two main groups: three belong to the Elicitation block, and Management runs across all of them. That two-vs-four framing is exactly why the count can trip you up — both numbers are right, at different levels.

1. Elicitation: Using different techniques to obtain requirements from stakeholders and other sources, then refine them in greater detail. It carries two sub-activities:

• Documentation: Describing the elicited requirements adequately, using natural language or conceptual models.
• Validation and negotiation: Checking that predefined quality criteria are met; requirements must be validated and conflicts negotiated early.

2. Management: Orthogonal to all the others — measures to structure requirements, prepare them for use by different roles, keep them consistent after changes, and ensure they get implemented.

Tip: Think "EDVM" — Elicit, Document, Validate, Manage. Three sit under elicitation; Management is the umbrella that never stops.

Go deeper:

• Requirements engineering (Wikipedia) — the elicitation, documentation, validation, and management activities and where they sit in the discipline.