There are a number of good books written on the subject of heraldry, so if you really want to learn all about it you should try "Boutell's Heraldry", revised by J.P. Brooke-Little, Richmond Herald of Arms (My edition is 1973 and there are probably newer versions). It has a great glossary. Another is "A Complete Guide to Heraldry" by A.C. Fox-Davies.
If you want to look up the blazons* for just about every Coat of Arms in England, Scotland, Ireland and Wales, check out "Burkes General Armoury" at your local library. There also similar publications for every country or region that has heraldry in it's history.
*Blazon: Heraldic description of Arms.
The full display of all the armorial bearings is called an " achievement of
arms" or simply "achievement". It is made up of several parts:
The Arms - or Shield of Arms (sometimes called Coat of Arms because in the days of chivalry arms were often displayed on a the surcoat as well as on the shield. Henry V, shown here as he was at the battle of Agincourt, wearing a surcoat. His shield bore the same devices.
The Arms (Shield) is the one essential part of the achievement, and in some cases may be all of it. However, most personal arms have at least a crest associated with it. More about shields later.
The Crest - is a device displayed on the helm (helmet).
This is an interesting crest from the arms of someone named "Ings".
Crests can be simple or extremely flamboyant. This one is described as "In front of two dragon's wings displayed gules, an escallop as in the arms". [Note: "as in the arms" means the escallop (scallop) is the same as one or more on the shield.]