Anyone beginning to study the complex but fascinating world of English heraldry will soon confront the rules of 'blazoning', that is describing in words the contents of a shield, or complete achievement of arms. (The latter means the shield, crest, supporters, motto, etc.) Note that purists avoid the term 'coat of arms' as a confusion with the 'surcoat' worn over armour, patterned like the shield.
Seeing a shield for the first time, and having blazoned it, the next step is to identify it. As there are many thousands of arms the chance of recognising more than a few is small. This is where Papworth's 'Ordinary' comes in.
Here virtually all the arms known are listed according to simple rules and moving through these step by step leads one to the family name concerned.
To an embryo, or experienced, herald, the book is indispensable and essential.
The copy I purchased is in beautiful condition, and arrived promptly. It is already working hard to justify its purchase!