Extracted from my coins and paper money collecting blog:
Uncirculated (UNC)
• A perfectly preserved note (100% new),
• Never mishandled by any parties.
• Paper is clean and firm, without discoloration.
• All corners are sharp and perfectly square, without any evidence of rounding.
• A UNC note will have it’s original, natural sheen and crisp.
About Uncirculated (AU)
• A virtually perfect note, with evidence of some minor handling.
• Condition may show very slight bank counting folds at a corner or one light fold through the center, but not both.
• An AU note cannot be creased – a crease being a hard fold which have “broken” the surface of the note.
• Paper is clean and bright with original sheen. Corners are not rounded.
Extremely Fine (EF)
• A very attractive note, with light handling.
• May have a maximum of three light folds or one strong crease.
• Paper is clean and bright with original sheen.
• Corners may show only the slightest evidence of rounding.
• An EF note may also have the slightest sign of wear where a fold meets the edge
Very Fine (VF)
• An attractive note, but with more evidence of handling and wear.
• A VF note may have several folds both vertically and horizontally.
• Paper may have minimal dirt, or possible color smudging.
• Paper itself is still relatively crisp and not floppy.
• There are no tears into the border area, although the edges do show slight wear.
• Corners also show wear but not full rounding.
Fine (F)
• A note which shows considerable circulation, with many folds, creases and wrinkling.
• Paper is not excessively dirty but may have some softness.
• Edges may show much handling with minor tears in the border area.
• Tears may not extend into the design.
• There will be no center hole because of excessive folding.
• Colors are clear but not very bright.
• A staple hole or two would not be considered unusual wear in a Fine note.
• Overall appearance is still on the desirable side.
Very Good (VG)
• A well used note, abused but still intact.
• Corners may have much wear and rounding, tiny nicks, tears may extend into the design, some discoloration may be present, staining may have occurred, and a small hole may sometimes be seen at the center from excessive folding.
• Staple and pinholes are usually present, and the note itself is quite limp but no pieces of the note is missing.
• A note in VG condition may still have an overall attractive appearance.
Good (G)
• A well worn and heavily used note.
• Normal damage from prolonged circulation will include strong multiple folds and creases, stains, pinholes, and/or staple holes, dirt, discoloration, edge tears, center hole, rounded corners and an overall unattractive appearance.
• No large pieces of the note is missing.
• Graffiti is commonly seen on Good notes.
Fair (F)
• A totally limp, dirty and very well-used note.
• Larger pieces may be half torn off or missing besides defects mentioned under the Good category.
• Tears will be larger and obscured portions of the note will be bigger.
Poor (P)
• A “rag” with severe damage because of wear, staining, pieces missing, graffiti and large holes.
• May have tape holding pieces of the note together.
• Trimming may have taken place to move rough edges.
• A Poor note is desirable only as a “filler” or when such a note is the only one known of a particular issue.