What does an AC rating mean on laminate or vinyl plank floors?

AC stands for Abrasion Criteria.  It means products have been tested for durability for abrasion, impact resistance.  The rating generally is from AC1 to AC5 but there are AC6 products as well.  They can be divided into both residential and commercial application.  The higher the number generally the more resistant to wear they are.  A general rule of thumb is an AC1 would be for low to moderate traffic in a residential application.  AC4 would be classified as moderate commercial or higher residential use.  AC5 rated for heavy commercial applications.  For residential an AC3 or AC4 would be suitable for families with higher traffic levels.  Ask your flooring representative to give you the details on the appropriate levels for your application.