Properties : A property is a precise condition that can be checked in a given state or across a number of states (for example, to describe behaviors in the case of temporal properties). It should specify what the condition must be, not how it is satisfied. The overall aim of model checking is to increase the quality of verification and validation (V&V) by specifying and checking properties that cover all of the application requirements.
The best time to capture the properties is during each relevant phase of the software lifecycle (requirement, design, development, and testing) and not after the fact.Whatever is known about the correctness and completeness of the application during each phase should be captured and preserved as additional information—ideally within, or closely associated with, the relevant artifacts—as the system is developed. This allows the designers, developers, and test personnel to be aware of all the properties and the related requirements.