Accounting and financial auditing in auditing firms in Morocco is a fundamental pillar in ensuring corporate transparency and compliance with national and international regulations. This book explores the conceptual foundations of auditing, highlighting the evolving needs and requirements of modern auditing. Through the audit charter, which serves as the official terms of reference, it describes the objectives and missions of auditing, incorporating practical case examples such as the audit of family-owned and multinational companies. It also examines the growing importance of auditing as an instrument of governance and management, particularly in areas such as information systems auditing and the fight against fraud. The book highlights the impact of audits on improving environmental performance and managing financial risks. In conclusion, it underlines that auditing, far from being a mere obligation, is becoming a strategic tool for creating value within companies.