One of the most widely and easiest systems for describing the size of a particular book is through the following definitions.  Books may also be broken down into very detailed measures, though for simplicity's sake we reference the Scale of the American Library Association and coding system as follows:

NEW / AS-NEW
Reserved for books that are brand new or were packed away direct from the distributors.  These books are free from any defect and/or handling evidence.

MINT (M)
Also known as Very Fine (VF).  The book and jacket have to be pristine with no absolutely faults or defects at all ...not even minor ones.  Many brand new books which are available on store shelves do not live up to this grade, so it is not to be confused with As-New.

FINE (F)
For a book to be considered Fine it should be free from obvious faults, though does not need to be absolutely perfect. The book can show minor signs of age and ownership but should be clean, tightly bound and square. A dust jacket should be free of chips or tears or any real faults and/or blemishes.  This grade allows a variance when one references the actual age of a particular book as it does allow for some loss of freshness and commonsense in relation to the books age. It is acceptable to have a previous owners name or annotation, though this should always be noted in the description.

There are also intermediate grades of near fine (NF) and Near Mint (NM).  This would denote a copy that does not quite meet the exacting standards but must still be a very nice copy. Some dealers may also reference this with a +/- in this grade.

VERY GOOD (VG)
A book showing some signs of wear. Any defects or faults must be noted.  Basically, VG and Good (G) covers the condition the average secondhand book fall under.  In other words, books that have obliviously been read and handled, but not abused.  Dust jackets may show loss, wear and tear.  Any faults should be mentioned such as inscription stamps, shipping and tears, etc.  Though not as nice as the higher conditions, a book in this grading category should still qualify as a collectable copy.  Variations of this grade may also use the +/- annotations to reflect a higher or lower quality of this grade.

GOOD
The book must be totally complete (as issued) and intact. Any defects must be noted.  There can be some fairly major faults with either the book or the jacket. Once again we would recommend every defect individually.  This grade may also include G+, which indicates a better than average G.

FAIR
A worn book that has complete text pages (including those with maps or plates) but may lack endpapers, half-title page, etc. Any defects or faults must also be noted.

POOR
A book that is sufficiently worn that its only merit is the complete text, which must be legible. Any missing maps or plates must be noted. May be soiled, scuffed, stained, or spotted, and may have loose joints, hinges, pages, etc.  Covers may be detached but should be noted.

The grading for vintage paperbacks will fall pretty much under the same guidelines as for hardback editions, though additional attention should be applied particularly to the covers and spine, as they are these areas are the most susceptible to any sort of wear & tear.  Softcover books are typically handled differently by their owners, and thus certain damages may occur that a hardcover book would not normally be subjected to.

Though the nature of defects found in collectable paperbacks are varied. Any defects may result in lowering the grade down from an otherwise fine book. Below are listed some the more common defects you might see mentioned in various dealer catalogs.  Any of these defects must be so noted when describing any book.

BUMPS
These usually appear on book corners. At the extreme, they could tear, crease, and/or warp the book from cover to cover. A mild bump may appear as a very slight bend with loss of sheen to the cover near the point of impact.

CHIPS or NICKS
These often occur at the top or bottom of the spine. They refer to removal of a small area of color or of actual cover stock.

CORNER CLIP
The removal of a triangular corner of the book.

CORNER CREASES, SPINE SPLITS and COVER TEARS
Self-explanatory.

CROSS-CRACK
Most common on very thin books, this is a crack across the spine. It can be minor (barely visible) or harsh (in which case the crack may extend onto one or both covers).

DARKENING or FADING
These problems may occur to covers, spines and interior pages. Most commonly, spines are faded by sun exposure and interior pages become darkened (and brittle) with age.

FRONT COVER LIFT
This happens when books are bound too tightly, causing the cover to raise or curl up slightly.

GLASS or CUP RING MARKS
These are visible on the covers of books used for coasters.

LAM LIFT or LAM PEEL
This refers to the thin clear film bonded (laminated) to the color image on the exterior of many early paperback books. As the books age and are rubbed against one another this lamination begins to peel back, fray or lift, at the book edges.

READING CREASES
These are lengthwise creases on the spine or on the book covers adjacent to the spine. They result from flattening the book when it is opened to read.

REMAINDER MARKS
This is a general term for a physical change made to a book by a publisher, distributor or bookseller to indicate that the book is non-returnable. These changes include rubber stamps (on covers or page edges), blind-emboss stamps, rounded and/or clipped corners, a neat sawcut on an edge, a punched-hole through the cover or marker stripes on the page edges.

RUBBING
This often reduces the gloss on the cover's surface without affecting the color of the image. An erasure can have the same effect on the surface.

SCRAPES
These can be scratches made to the surface by a sharp implement. Edge scrapes occur when the book edge is dragged over another sharp edge creating a series of small scuffs that remove color.

SCUFFING
This can mean anything from very slight dulling of covers (where the book was rubbed along a shelf or against another book) all the way to amore serious bruise removing some of the color layer.

SPINE ROLL
The spine has been bent lengthwise so that, looking down at the book, this spine is not at right angles to the covers.

STICKER-PULL / STICKER RESIDUE
Discoloration or the actual removal of cover color by pulling off a price sticker.

STORE STAMP (S/S)
These often appear on front endpapers. This defect is more serious when it appears on the exteriors of covers.

TAPE REPAIRS, LOOSE PAGES and MISSING PAGES
Self-explanatory

WARPING
Books which are bent or rippled. This can occur from being improperly bound, poor storage or handling, or from water damage.

WATER DAMAGE
This is sometimes visible on covers and often on interior pages or page edges. Discoloration of tinted page edges sometimes results, as does rippling or warping.

NEW / AS-NEW
Reserved for issues that are brand new or were packed away direct from the distributors.  These books are free from any defect and/or handling evidence.

MINT
100& complete, no chips missing or damaged pages inside or out.  No odors or curls, and must be 100& flat.  No foreign additions (such as mailing labels, etc) on the cover, spine or interior.  Colors must be bright, pages white, and staples (if evident) must be clean and true.  Not even the slightest bump or crease can be present in this grade.

FINE
Any portion may have a rare tiny edge tearing, usually at top or bottom.  Issue must still be odor free and nice and flat.  Spine may have small creases and cover may have small price sticker.  Pages may have a few rare small creases/folds but pages must still be bright with vivid colors.  Issue must be 100% complete and staples (if evident) are clean.

VERY GOOD
Parts of the spine paper may be missing, usually at the top and/or bottom.  Pages may have edge tears and/or chipping.  May be missing one staple and staples can show some rust.  Does not need to be 100% flat.  The issue may have loss of a small chips here and there, and any inserts may have been removed.  Overall tightness is described as being partially attached to the covers or binding.  Cover and spine may show evidence of creases, subscription label or stamps, and may have creases, writing, tape, tape remains, re-gluing and/or dry stains.  Pages may have handwriting but must be noted as such, and fading or stiffness is evident.

GOOD
Parts of the spine paper or entire spine may be missing.  May also have loose or detached pages (which must be noted), and may be missing parts of pages due to cut out or tearing out.  The issue might be missing one staple and staples may show rust.  The cover may be completely loose.  An obviously worn issue and typically any issues are not regarded as collectible in this grade (or lower) unless to be used as filler or for a rare edition.

FAIR
Issue may be incomplete.  Missing pieces on cover or interior.  Major creases, tears, stains and folds will quickly knock an issue down into the fair grade.  Pages may have underlining and annotations.