Data privacy and security are critical challenges, particularly when handling sensitive or proprietary information. Data visualization consultants must ensure that they comply with data protection regulations such as GDPR or CCPA, and implement secure data handling practices. This may involve anonymizing or aggregating data before visualization, restricting access to certain datasets, and ensuring secure data storage and transmission. Data visualization consultants must also educate clients on the importance of data security within visualizations, such as limiting data drill-downs that could expose sensitive details. Balancing transparency with security and privacy requirements is a delicate but essential task.