Meaning of the codes that state the condition of a record and its cover

S (Sealed)
Cover : The record is still packed.
Record : The record is still packed.

M (Mint)
Cover : Cover and extra documents like lyric sheet, booklet or poster are in perfect condition.
Record : The record is in brand new condition, absolutely perfect.

NM (Near Mint)
Cover : The cover should look close to perfect with only minor signs of wear and or age. Minor impressions to the cover (due to the outer edge of the record resting inside) may be acceptable, however the artwork should be as close to perfect as can be.
Record : Describes an almost mint record, this grade is used for records that appear virtually flawless but not perfect. A very minor scuff can appear on the record. Yet, the record must play without any noise over the flaw and the latter must be very hard to detect. Any blemish affecting sound quality will prevent records from being graded NM or M.

EX (Excellent)
Cover : The cover and packaging might have slight wear but excellent aspect overall.
Record : The record shows some signs of having been played, but there is very little lessening in sound quality.

VG++ (Very Good ++)
Cover : The cover and packaging might have slight wear but excellent aspect overall.
Record : The record shows some signs of having been played, but there is very little lessening in sound quality.

VG+ (Very Good +)
Cover : Cover shows some handling imperfection like normal wear and tear, price tag, creasing... Cover can also be in mint condition but there is a DJ or promo copy stamp or cut in the corner.
Record : Most common condition for records. The record has been played a few times but displays no major deterioration in sound quality, no wear, despite occasional light marks.The average person would not notice anything wrong.

VG (Very Good)
Cover : Cover suffers from folding, scuffing of edges, spine splits, discoloration ...
Record : Now the signs of age and handling are starting to show. You can notice some clear wear on the surface, there is some noise (pops and crackles). There may be minor warps and skips (better to ask for confirmation to the seller especially if your turntable is sensitive).

VG- (Very Good -)
Cover : Cover suffers from folding, scuffing of edges, spine splits, discoloration ...
Record : Now the signs of age and handling are starting to show. You can notice some clear wear on the surface, there is some noise (pops and crackles). There may be minor warps and skips (better to ask for confirmation to the seller especially if your turntable is sensitive).

G (Good)
Cover : The cover and contents can be torn, stained and/or defaced, there also can be some writing on it.
Record : The record has been played so much that the sound quality has been noticeably deteriorated, perhaps with some distortion and mild scratches.

B (Bad)
Cover : The cover and contents are badly damaged or partly missing. Cover can also be missing.
Record : The record does not play properly due to scratches, bad surface noise, etc ... Unless it is something very rare it is not worth listing in this condition.

NA (Not applicable)
Cover : The cover is missing or this code is not applicable for that kind of item (Plain white or black sleeve, books, merchandising ...).
Record : The record is missing or this code is not applicable for that kind of item (books, merchandising ...).