Mint (M): Perfect condition, which basically means that it is as good as new, literally. The vinyl has to look new and sound as though it was never played, and the cover has to look untouched. Some argue that the only mint records are brand new, unopened ones still in their original packing.
Near Mint (NM): Vinyl is near perfect. At most, a light scuff appears on the record, but it should play without any noise or skips. The record sleeve should also be nearly perfect, with only minor signs of wear. There should be no "ring wear" on the cover. (Ring wear is when the outline of the record inside shows through the sleeve.)
Excellent (EX or VG++): Vinyl should still play with no skips of any kind. There can be some very minor surface scuffs, but they should not affect the sound quality. The record sleeve can have some minor ring wear, but it should be mostly in good shape. Also, there can be some minor creases in the corners, but no splits in the seams.
Very Good+ (VG+): This is the grading category where the quality of the sound is affected — there will be some surface noise — and the vinyl will show wear, including surface scuffs and some light scratches. However, the record is still very listenable as there are no deep scratches that cause skips. On the cover, the corners may be slightly bent, but not broken. There may be wear to the seams but not tears or holes.
Very Good (VG): Vinyl doesn't necessarily look good, but still plays well enough. Surface noise will probably be present, including pops and clicks. At higher volume levels, the music should overpower any pops and clicks present. There may be seam splitting, but not complete separation of the sleeve panels from each other. There will be noticeable ring wear on the cover, but the cover should for the most part still be in good condition.
Good (VG-): Vinyl is well-played and looks it. However, the record should still play without skipping. It will have substantial surface noise, pops, and clicks. Loss of various parts of the dynamic range will occur due to worn grooves. This grade depends a lot on the owner and the type of records he or she collects. A rock record may still sound OK at a high volume, but quieter styles of music will be practically unlistenable. The record cover may have many problems, including seam splits, tears, and writing on it.