Mead is an alcoholic beverage made with honey as the primary fermentable ingredient. It can include other ingredients such as fruits, herbs, spices, etc.
The craft has changed considerably since the legalization of homebrewing in the US. Be wary of old information. This is especially true of information 10 or more years old.
You might want to start with The Basics. Note, however, that heating the must has fallen out of favor of many meadmakers as a pointless step. If you aren't heating anything, it takes a while to mix in the honey, but it will dissolve eventually. A drill with a mix-stir attachment makes this process much faster.
For a thorough and reliable reference, consider buying a copy of The Compleat Meadmaker by Ken Schramm. It's due for an update, but it's still the densest source of meadmaking information in print. The most important updates are that author no longer heats most of his musts at all, and he uses staggered nutrient additions (addressed below).
The BJCP Mead Exam Resource page has links to articles on a variety of related topics. Some of it is very old, but luckily most of the links are dated in some way.
This list is not exhaustive.
The defining ingredient of mead. Roughly 80% sugars by weight.
Used to dilute honey. May not be necessary in some melomels in which juice suffices for this purpose.
Saccharomyces cerevisiae is a fungus that that consumes certain forms of sugar and releases, as waste, ethanol and CO2 gas.
Every good mead recipe takes into account that honey is devoid of substantial nutrition. Without bolstering the nutrient content of a mead must, the yeast will have trouble doing their job and may not even gain a foothold. Nutrient sources include fruit, diammonium phosphate, pulverized yeast hulls, and various additive products produced by yeast companies.
Mead flavored with fruit is called melomel. Some fruits lend a specific name to mead they flavor. In the case of apples, that name is cyser.
Mead flavored with herbs or spices is called metheglin. Some herbs and spices also lend special names to mead that contain them. Roses, for example, make rhodomel.
Try one of the Beginner recipes found here!
A number of recipes found online call for bread yeast. If you've brewed before, you know just how big of a difference the right yeast and yeast handling can make. Think twice before using bread yeast. Instead, use a yeast more suitable to mead, and take the minimum steps to ensure a healthy pitch.
You may see people talking about aeration during fermentation. Mead benefits from aeration (adding O2) and degassing (removing CO2) the must for the first third (or so) of fermentation - speaking in terms of the drop in specific gravity, not time. This is not completely necessary and you can feel comfortable ignoring this step for your first few meads. If and when you do attempt this step, however, it is important to remember that the CO2 can come out of solution rapidly, causing foam-overs or geysers if you are not careful.
Mead also benefits from staggered nutrient additions. This means that you introduce the nutrient additives over time. This provides resources for the yeast when they need it without causing a spike in fermentation speed and temperature. You can also ignore this step until you're comfortable with the equipment and process.
You can find a few Recipes on this wiki.
Finally, remember that mead is forgiving if you follow the most basic of rules.
Once you get a few batches under your belt, you'll want to start testing out your own ideas. When you reach that point, here are a couple of things to keep in mind.
Learn to use the GotMead calculator. Note that it has a help page. This is the single most helpful tool (other than experience) in formulating recipes. Be aware that the calculations will inherently yield ballpark numbers, as honey content will vary.
The other big stumbling block is yeast nutrition. Mead musts are extremely nutrient deficient. There really isn't any short answer for how to supplement the required nitrogen and micronutrients. Before you start formulating your own recipes, you'll want to settle in and read Advanced Nutrients in Meadmaking. This also covers staggered nutrient additions to some degree. The MeadMakr BatchBuildr is an excellent resource which can help you calculate your nutrient additions and dial in your process.