Artist proofs are the first pieces produced for an edition, they are labelled a/p and normally represent 10% of the main edition size, so an edition of 300 will have 30 artist proofs (so 330 pieces in total), although there are exceptions to this. Traditionally the artist proofs had subtle differences worked on by the artist (however in the case of Kerry Darlington’s work the whole edition is often unique). Artist proofs are rarer than standard editions and only usually available for a new release. Artist proofs often sell at the same price as the main edition however they can demand a premium on the secondary market as they are more sought after. Many collectors like the fact they are produced first and often collectors have an all artist proof collection.
The H/C edition stands for Hors de Commerce (meaning not for sale), it's a less used sub edition and was usually kept by the publisher. Today the H/C's are often sold and have an added rarity value like the other proofs.
The P/P edition stands for printer's proof, it's also a less used sub edition and was kept by the printer often as part payment. Today they have an added rarity value like the other proofs.
It is the personal preference of the client as to which edition suits their collection, most artists (such as Kerry Darlington) produce A/P's as part of the edition but rarely H/C or P/P . So if a client wants their collection to match then the Artist Proof is a good choice.
This is a short explanation of the way that many of our artists produce proofs, artists can employ a different approach. The way proofs were used in previous years was quite different.