What is risk-based testing?

Risk based testing starts with accessing risks related to complexity of logic, business criticality, defect prone areas in application, frequency of use of sensitive computation of application features. This involves priority of testing those areas of an software that involve critical features and functionalities that are likely to fail. Such type of testing involves experienced testers that have understanding of possible risks involved in mission critical applications.
Positive impact of risk based testing are opportunity to learn and improve business sustainability when you test application based on the risks involved negative impact of risk based testing are threat of customer dissatisfaction, impact of overall project cost due to detailed testing, bad or negative user experience, and possible loss of customers.