Here’s a really good, up-to-date overview of the UX practice.
A user experience audit is the process used to identify potential usability issues based on established heuristics and/or prior user research. A successful audit provides an organization with a clear picture of positives and pitfalls with the current product experience and can help to target what to focus on in future design enhancements.
Source: Conducting A UX Audit: What You Need to Know | UX Booth