Heuristic evaluation is one of the most common types of expert reviews for Web sites.  It was developed by Jakob Nielsen.  In the book, The Design of Sites, by Douglas K. Van Duyne, James A. Landay, Jason I. Hong, the authors explain heuristic evaluations.

What Is a Heuristic Evaluation
Van Duyne, Landay, and Hong write:

“The basic idea is to have three to five expert judges independently evaluate a site, using a list of usability heuristics or principles.“

How To Perform a Heuristic Evaluation
Van Duyne, Landay, and Hong write:

“In a heuristic evaluation, the judges go through the site, often with a set of sample tasks as a guide, looking for violations of the heuristics.  They note each violation and make a suggestion for fixing it. ... The judges also rate each violation with a level of severity.  Severity levels are usually assessed on the basis of the expected customer impact and frequency of the violation.”

7 Design Principles / Heuristics (The Design of Sites)

1. Be consistent throughout.
2. Offer informative feedback.
3. Rely on recognition over recall.
4. Help customers prevent and recover from errors.
5. Support customer control and freedom.
6. Help frequent customers use accelerators.
7. Strive for aesthetic and minimalist design.

10 Usability Heuristics (Jakob Nielson)

1. Visibility of system status.
2. Match between system and the real world.
3. Use control and freedom.
4. Consistency and standards.
5. Error prevention.
6. Recognition rather than recall.
7. Flexibility and efficiency of use.
8. Aesthetic and minimalist design.
9. Help users recognize, diagnose, and recover from errors.
10. Help and documentation.

For an explanation of Jakob Nielson’s 10 usability heuristics, see Ten Usability Heuristics.