Dried Herbs are herbs that have been dried, usually deliberately. This drying achieves two things: it preserves the herbs for storage, and, concentrates the flavour.
You can get two conflicting sets of opinion about the flavour of dried herbs: the first is that they are much stronger than fresh, so use less of them; the second is that they have no flavour at all. You will almost certainly find, though, that the ones which have no flavour were probably dried a very long time ago and have been hanging around on a shelf forever. Those who do manage successfully to dry their own herbs swear by them, saying how much more flavourful they are compared to store-bought ones dried herbs.
That being said, you do have to approach the flavour of most dried herbs as being different from that of the fresh version of them. The flavour will be different: not better, not worse, just different. And while that won't cut it at all in certain recipes, such as pesto and tabbouleh, it's perfectly fine in many others.
Dried herbs are far more convenient and less expensive than fresh ones are, unless you live somewhere where you have an abundant stock at your back doorstep year round, which most people don't.
The only time you might need to soften herbs first in water is if you were making something such as herb butter with dried herbs, but then just making it a few hours before you use it should also do the trick. That will allow plenty of time for the moisture and fat in the butter to make the herbs supple again.
Some people say add dried herbs at the beginning of cooking, fresh ones at the end: it's probably best to disregard such a generalization, and follow the rule for the specific herb as to what point in the cooking it should be added.
Many people suggest crushing dried herbs to release the full flavour before being added to a recipe.
Another rule is to reduce tablespoons to teaspoons, but they both work out to be the same:
2 tablespoons (6 tsp) fresh chopped parsley = 2 tsp dried parsley.
"fluffier" dried herbs (e.g. parsley): 6 tablespoons = .35oz = 10g
"denser" dried herbs (e.g. basil): 4 tablespoons = .35oz = 10g
When drying your herbs from your own pot or garden patch, cut them before they flower: at this point, they will have the most oil in their leaves. If they've already flowered, you can still harvest and dry them, it's just that before flowering is optimal.
Opinions differ on whether to wash herbs before drying or not. Some say don't, unless they are obviously dirty, as washing them will remove some of the flavouring oils from the leaves (heavens, what are you supposed to do if it rains on the poor things, race out with an umbrella?). Others say do wash them, just make sure they are thoroughly dry on paper or cloth towel before starting the drying process so that mould doesn't start. The ones who say don't wash them may well be thinking of herbs from their own garden or pots, so they know exactly what was and what wasn't sprayed on the herbs.
Probably everyone has tried to dry their own herbs at home, doing the "en provence" thing of tying the herbs in bunches and hanging them upside down from various places in the kitchen or dining room, trying to choose the most advantageous spots for maximum dramatic viewing effect. What you end up with of course, is a bunch of yellowed, dusty weeds that eventually look so bad you take them down and toss them out.
If you are going to hang them, you can't leave them up that long -- leave them hanging just until the leaves will crumble off the stems into your hand, then get them down and into a container. If your herbs tend to get dusty while hanging, put them in a paper bag with holes punched in it. The paper bag is also handy as you can write the name of the herb, and the date you set them to dry, on the bag. Most herbs will need a minimum of two weeks to dry. During that time, they shouldn't be exposed to direct sunlight. Don't hang herbs above your stove, no matter how quaint it looks.
When drying your own herbs, "low and slow" is the best way -- meaning low heat, as in room temperature. The water in the herbs needs to dry slowly so that it will leave the essential oils behind. Some advice has you running the oven for a few hours to dry herbs quickly in it. Drying in the oven causes a quicker evaporation so that some of the oils are caught up with the evaporating water. Besides, how much did running the oven cost you compared to just buying a jar at the store? Though microwaving the herbs to dry them will reduce the energy usage, microwaving them does cook them a bit.
You can also dry herbs in the fridge (remember, the fridge is one of the driest places in your house). Make sure the herbs are completely dry first to avoid mould. Arrange them on a plate and set in fridge uncovered for about a week or until they will crumble in your hands, then package. Many feel that herbs that are fridge-dried retain colour and flavour better than those that are dried out in the open air.
If you live in the UK and have an airing cupboard, this can be an ideal place to dry herbs, low and slow.
If any herbs develop mould while drying, toss the whole bunch. To store when dry, strip the leaves off the stalk by running the stalks through your fingers. There is no point in rubbing or crushing them any more than necessary at this stage, as the less surface exposed to air the slower the loss of flavour will be.
The main trick with Dried Herbs is storage: store them in a sealed container away from the light. This means you can use glass jars or sealable plastic bags if you will be storing them inside a closed cupboard, otherwise, if they will be out in the open don't use glass jars: use metal or plastic ones instead. Dried Herbs are good for up to a year from when they were dried and packaged.
As Dried Herbs get older, there is a flavour loss and you need to use more. The exception is sage, which seems to actually develop more flavour in storage.