Which type of knowledge is considered 'tacit knowledge'?

Tacit knowledge refers to the understanding and skills that individuals acquire through personal experience and practice, which is often difficult to articulate or document. This type of knowledge is usually context-specific and gained through direct involvement in activities, making it deeply personal and tied to the subtleties of individual experiences. Such knowledge is critical in fields that require intuition, judgment, and insight, as it often includes insights that cannot be fully expressed in words.

In contrast, the other types of knowledge outlined in the options tend to be more structured and explicit. Knowledge documented in manuals is codified and can be easily shared and transferred, while quantifiable knowledge is typically expressed in measurable parameters and can be systematically analyzed. Theoretical knowledge gained in classrooms is also explicit, often grounded in established principles, theories, and models that can be studied but may lack the practical insights derived from experience.