AU-C Section 200.08-10. The Audit Process

AU-C Section 200.08-10 says:

"08. GAAS contain objectives, requirements, and application and other explanatory material that are designed to support the auditor in obtaining reasonable assurance. GAAS require that the auditor exercise professional judgment and maintain professional skepticism throughout the planning and performance of the audit and, among other things,

• identify and assess risks of material misstatement, whether due to fraud or error, based on an understanding of the entity and its environment, including the entity's internal control.
• obtain sufficient appropriate audit evidence about whether material misstatements exist, through designing and implementing appropriate responses to the assessed risks.
• form an opinion on the financial statements, or determine that an opinion cannot be formed, based on an evaluation of the audit evidence obtained.

.09 The form of opinion expressed by the auditor will depend upon the applicable financial reporting framework and any applicable law or regulation.

.10 The auditor also may have certain other communication and reporting responsibilities to users, management, those charged with governance, or parties outside the entity, regarding matters arising from the audit. These responsibilities may be established by GAAS or by applicable law or regulation." 

 
The structure of the AU-C sections in GAAS include various sections designed to help the auditor throughout planning and performing the audit:

• Introduction: provides a high-level overview or background information for how to use the AU-C section and how it should be implemented.
• Objectives: explain what the auditor should accomplish by implementing the requirements of the AU-C section.
• Definitions: explain various technical terms used in the AU-C section that might not be clear from other areas of the text. 
• Requirements: include the specific rules the auditor should follow in order to achieve the AU-C section's objectives.
• Application and Other Explanatory Material: provide an interpretation and additional guidance on how to follow the requirements.

The auditor should use his professional judgment and professional skepticism in following the requirements of GAAS throughout the following three stages of the audit:

• Identify and assess risks of material misstatement: the auditor explores where the financial statements are likely materially misstated by understanding the entity and its environment, and understanding the internal controls that are in place to prevent and detect misstatements.
• Obtain sufficient appropriate audit evidence: the auditor designs procedures and obtains evidence to reduce the risk that the financial statements might be materially misstated.
• Form an opinion on the financial statements: the auditor forms an opinion of whether the financial statements as a whole are materially misstated based on his evaluation of that evidence obtained.

The opinion the auditor makes on the financial statements depends on the financial reporting framework used as well as the laws and regulations applicable to the entity.  In addition to the opinion report, the auditor might be required to issue letters to management (AU-C Section 265), those charged with governance (AU-C Section 260), and potentially other third parties, regarding matters arising during the audit.

https://www.aicpa.org/content/dam/aicpa/research/standards/auditattest/downloadabledocuments/au-c-00200.pdf