A record in mint condition should be in perfect, brand new condition. There should be no evidence of wear and tear, and the vinyl should show no signs of having being repeatedly played.
Near Mint (NM)
As the name implies, a near mint record should be almost perfect. The vinyl should show no more than the most minor of defects and the sleeve should be practically flawless. Typically, a record in Near Mint condition would be Mint but for possibly one small defect, maybe a minor surface abrasion on the vinyl or a tiny crease on the sleeve.
A record in Excellent condition will show signs of use in that there will be some light scratches or surface abrasions on the vinyl, but this will not affect the sound quality in any way. The sleeve may have some tiny amounts of scuffing or have some small creasing in the corner tips.
Very Good (VG)
A record in Very Good condition will have numerous light scratches or scuffs on the vinyl, but it should still play without noticeable deterioration of the sound quality. The sleeve may have a small split, or have noticeable scuffing and creasing along the edges. The label may be slightly discoloured and some ring wear may be visible.
An record in Good condition can be played without hopping or skipping, but there may be some hissing or extra surface noise. The sleeve will have some seem splits, scuffing, creasing, and may also be discoloured. Ring wear may well be visible and inner sleeves may show signs of wear and tear.
A record in Fair condition can still probably be played, but the sound quality will not be good, possessing surface noise and bad scratches. The outer and inner sleeve will be badly worn, creased or torn.
A record in poor condition may be unplayable in that the vinyl may be cracked, warped, or have several deep scratches. The sleeve may be torn, split, badly creased or have been defaced or written on. The inner sleeves may be unoriginal or missing.