A lot of us use medieval or medievalesque settings for our work. I myself am not using such a setting at present, but still find heradlry and blazonry useful and interesting.

For the uninitiated, I'll give a crash course:

Heraldry is the profession, study, or art of creating, granting, and blazoning arms and ruling on questions of rank or protocol, as exercised by an officer of arms. (Wikipedia)

Coats of arms originated as devices on shields used to identify particular nobles in battle. As such, they had very specific rules, most of which still hold today, designed to ensure clarity, visibility, and distinctness.

Blazonry refers specifically to the art of blazoning arms (describing them in the precise but flexible language of heraldry) and emblazoning them (drawing them based on their blazon; that is, their description in words.) I personally find heraldry and blazonry fascinating, and would like to see them used more in fantasy. To that end, I'm sharing these resources that I found online.

First of all: The Coat Of Arms Design Studio is a program, with a free and a paid version, that can be found at the link. It allows you to put together coats of arms fairly quickly and easily, although it neither blazons nor emblazons, and does not enforce heraldic rules such as the rule of tincture.

The Wikipedia article on Heraldry is a good place to start IIRC for learning the very basics.

For learning blazonry, I have found this tutorial to be a helpful introduction. It deals in particular with Canadian heraldry, and so to learn the details of any particular country's heraldic traditions, you'll have to go elsewhere, but it's an excellent introduction to blazonry for one who already knows the basics of heraldry, such as the names of the ordinaries, the rule of tincture, etc.

If you use heraldry in your story, please let me know! I'm always interested. I'd be fascinated to see your characters' coats of arms, too, if you care to share them. This thread is also the place for sharing heraldry resources I may have failed to include, if you have any.

And, as a final note, if you're interested in blazonry, but don't yet know it well, this will be an interesting test: See if you can use the resources I've shown you to emblazon these arms:

Gules, on a saltire azure fimbriated argent thirteen mullets of the third.

Hint: I do not require the emblazoned arms on a shield, and you should be able to find them online without making them yourself if that's your inclination. I will accept that as just as valid as emblazoning them by hand.

Extra Hint: If no one gets it and I show it to you, most of you will recognize it, even if you didn't bother to read the rest of the post or the resources I linked.

Moving to Culture since Heraldry is a cultural concern.

You, sir, gave me quite a start.

I'll have some of it in the fantasy project that's making me wrack my brain for a name, but it probably won't be to accurate, or detailed, because it's in a dreamworld.