Audit:

The audit is the process of checking the financial statements of a company `to ensure that it is 100% authentic and free from any kind of bias or fraud.

Fraud:

Fraud means the willingly wrong representation of something, to hide some material facts from outsiders or mislead them about some facts.

Professional skepticism:

The audit presumes that there are chances of revenue fraud before the audit process so that he can check the financial statement as per that mindset.