How to take requirements

Requirement: is a condition or capability a system must have.
The requirements of a software-intensive system are dynamic. You must expect the requirements to change during the life of a software project.
System’s true requirements (STR): those that weigh most heavily on the system’s economic and technical goals.
Identifying the STR is a continuous process.
It is impossible to completely and exhaustively state a system’s requirements before the start of development.
As a new or evolving system changes, a user’s understanding of the system’s requirements also changes.

Activities of the active management of requirements:

Eliciting, Organizing, and Documenting the system’s required functionality and constraints.
Evaluating changes to the requirements and assessing their impact.
Tracking and documenting trade-offs and decisions.

Why is important?

Offers solutions to the root causes of software development problems:

A disciplined approach is built into requirements management.
Communications are based on defined requirements.
Requirements can be prioritized, filtered, and traced.
An objective assessment of functionality and performance is possible.
Inconsistencies are detected more easly.
With suitable tool support, it is possible to provide a repository for a system’s requirements, attributes, and traces, with automatic links to external documents.

What are the “suitable tools” for requirements management?