What are the four core activities of Requirements Engineering according to ISO/IEC/IEEE 29148:2011?

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.