According to the BABOK® Guide v.3:
Business analysis is the practice of enabling change in an enterprise by defining needs and recommending solution that deliver value to stakeholders. Business analysis enable an entreprise to articulate needs and the rationale for change, and to design and describe solution that deliver value.
The six core concept mentioned (Need, Change, Solution, Stakeholder, Value ans Context) are the fundamental to practice business analysis. They are called the Business Analysis Core Concept Model™.
Becoming a Business Analyst 