The primary responsibility of an auditor is to express an opinion on the fairness of the financial statements. This opinion is based on the auditor's assessment of the risks of material misstatement in the financial statements and the results of the audit procedures performed.

The three types of audit opinions are unqualified, qualified, and adverse. An unqualified opinion is issued when the auditor has obtained sufficient appropriate evidence to support the conclusion that the financial statements are free from material misstatement. A qualified opinion is issued when the auditor has obtained sufficient appropriate evidence to support the conclusion that the financial statements are free from material misstatement, except for a specific matter. An adverse opinion is issued when the auditor has obtained sufficient appropriate evidence to support the conclusion that the financial statements are not free from material misstatement.

The purpose of internal control is to prevent fraud and errors, ensure the accuracy and reliability of financial information, and promote operational efficiency.

The five components of internal control are control environment, risk assessment, control activities, information and communication, and monitoring.

The purpose of an audit risk assessment is to identify the risks of material misstatement in the financial statements, assess the likelihood and magnitude of the risks of material misstatement, and design and perform audit procedures to respond to the risks of material misstatement.

The two types of audit procedures are risk assessment procedures and substantive procedures.

The purpose of risk assessment procedures is to obtain an understanding of the entity and its environment, identify the risks of material misstatement in the financial statements, and assess the likelihood and magnitude of the risks of material misstatement.

The purpose of substantive procedures is to obtain evidence about the accuracy and completeness of the financial statements, detect fraud and errors in the financial statements, and evaluate the effectiveness of internal control.

A management letter is issued to management, while an audit report is issued to the shareholders. A management letter contains recommendations for improving the entity's internal control, while an audit report contains the auditor's opinion on the financial statements. A management letter is not required by law, while an audit report is.

The purpose of an audit committee is to oversee the financial reporting process, review the auditor's report, and approve the selection of the auditor.

Internal auditors are employed by the entity, while external auditors are independent of the entity. Internal auditors focus on operational audits, while external auditors focus on financial audits. Internal auditors report to management, while external auditors report to the shareholders.

The purpose of an audit trail is to provide a record of the transactions that have been processed, allow auditors to trace transactions from the source documents to the financial statements, and help management identify and correct errors.

A financial statement audit focuses on the accuracy and completeness of the financial statements, while an operational audit focuses on the efficiency and effectiveness of the entity's operations. A financial statement audit is required by law, while an operational audit is not. A financial statement audit is performed by external auditors, while an operational audit is performed by internal auditors.

The purpose of a peer review is to assess the quality of an auditor's work, ensure that auditors are complying with professional standards, and help auditors improve their skills and knowledge.

A disclaimer of opinion is issued when the auditor has not obtained sufficient appropriate evidence to support an opinion on the financial statements, while an adverse opinion is issued when the auditor has obtained sufficient appropriate evidence to support the conclusion that the financial statements are not free from material misstatement. A disclaimer of opinion is not more serious than an adverse opinion. A disclaimer of opinion is required to be disclosed in the notes to the financial statements, while an adverse opinion is not.