Because of the constant low-level of Magic pervasive in the world, many people who are not otherwise magically inclined know one or two simple tricks or illusions. A slightly more fancy slight-of-hand or a cantrip to distract the easily distracted. Or maybe a naturally good speaker has inadvertently learned something like a simple charm spell.
These cantrips can be cast with a word or two or perhaps a weird twisting of one's fingers in the air. Or perhaps require a small token as a focus. They can be learned in an afternoon and perfected over a few weeks and hardly count as real magic.
People who actually devote effort into learning the basics of magic - Mages, witches, clerics, and other types of Magic users - are uncommon, but not rare in the valley. Learning a wide variety of low level spells can be easily done in a few seasons and with some practice, a person can make a decent living providing simple magical support to a community.
To learn more than simple Magic takes great effort and often one has to go to high Magic areas like Elven cities. Learning to cast powerful magics involves being able to draw Magic from a wide area and takes a great deal of practice and concentration and years of training.
Powerful mages are rare and it would not be uncommon for their names to be widely known and spoken of as near mythical superbeings even if they are only a little more powerful than a local mage.
Because Magic in an area is usually lowly concentrated, mages can rarely cast un-prepared spells.
Mages will often spend time, mental energy, and some few ingredients focusing magic into a small token or rune, sealing the spell for later activation when needed. The weaker the magic in an area and the more powerful the effect, the longer the spell will take to prepare.
Tokens can take the form of small gems, coin shaped discs with special carvings, specific runes carved in a staff, or any other small pocketable item. Normally more powerful spells will require larger tokens. Larger tokens will also hold the spell for longer.
Tokens will also usually be closely aligned with the spell being cast. Light spells bind easier to bright gems. Combat spells bind better to obsidian or raw iron. Healing spells bind stronger to liquids, clean cotton, or poultices.
As a mage grows in skill, they can more quickly channel the Magic into a token. Given enough concentration and time, even a low skilled mage can prepare a fairly powerful spell, but they risk the spell going off early or without great effect if they do not take the time to do it right.
Depending on the skill of the mage, they can have a number of spells prepared as tokens or bound to specific runes on a staff that are ready to go. The more skilled the mage, the greater number of spells they can have ready or the higher powered the spells can be. Keeping tokens ready takes awareness and occasionally pauses to re-focus the magic or the "charge" will evaporate with time. Most tokens will evaporate in a day or two with more powerful spells taking more constant concentration and will evaporate faster.
A mage will always know which of his tokens are charged and ready as well as which spells are associated with which token. They can usually sense when an object has been used as a token by another mage, but will not be able to determine which spell the token is associated with other than a general sense of the associated level (a powerful spell will fell "heavier" than low level one).
A sufficiently powerful mage can prepare tokens so elegantly that lower mages will not even sense the cast.
When activated, the spell will discharge the stored magic as well as pull some magic from the local area to cause its effect. Spells can be activated sometimes by rubbing the rune and erasing the binding; a brief mental tick; waving the token in the air; the invocation of the final words of the spell; or even by throwing the token at the target. The exact trigger is often tied to the spells effects, but is also influenced by the caster.
Usually simple tokens like this are "discharged" and fully used after one use but can be recharged and re-used; however some very powerful spells will cause the token to be destroyed in order to activate the spell.
Mages will often have their own pseudo language they will speak to invoke their spells "Hocus Pocus!" or "Blowit Upus!". The mage will use their own language to focus their mental abilities rather than trying to learn the nuance of some ancient language that is as likely fake as the mage's own. Any spell token can be activated by a pseudo invocation, but spells that explicitly require a verbal component usually require specific mental thought processes so will require the mage to recite the same words he learned originally to cast it in (even if the words are made up).
Enchantments and permanent castings
With great effort simple spells can be enhanced into more permanent castings and enchantments. Permanent castings can be re-used without the normal effort of re-creation but will take longer to re-charge after use since they will have to draw from the local mana. Permanent castings do not evaporate like tokens and do not take any effort to maintain.
A mage can have any number of permanent castings, but because they draw from local magic rather than pre-stored magical effort, using more than a few will quickly drain most areas of available magic. Most mages will not carry very many permanent castings for fear that the castings will absorb too much magic and drain and area, triggering far more problems than the effort is worth.
Mages will normally be able to detect permanent castings and enchantments for no other reason than the mage will be able to sense the way the enchantment pulls on the local fairy dust to stay charged. They will be able to detect the enchantment unless the original caster went to great trouble to hide the effort or disguise the enchantment.
Binding a spell into a specific rune or gem can allow even non-magic users to cast the spell if they know how. Binding a spell does not necessarily make it available to anyone else, it takes special effort to allow anyone but the original caster to trigger the spell.
Staves and magical batteries
Since enchantments have to draw magic from the surroundings, a common enchantment younger mages seek is to enlist a more experienced mage to create a binding enchantment on a slate or staff that can act as a "battery" to help their runes cast correctly or with more force. The staff will recharge slowly, but does not take any effort to maintain, and that extra kick can often be the difference. Experienced mages will often carry multiple batteries in the form of staves, rings, and even enchanted robes; and will frequently seek out mana rich areas to recharge before major castings.
Tokens vs Enchanted Gems
Casting tokens are unlike truly enchanted gems or runic bindings. In the case of casting tokens, the spell will be bound to the casting mage. If the token or rune is separated for too long from the originating mage, the spell will evaporate and must be re-bound.
The creation of the token takes time and effort, but the creation binds magic into the token and makes it available later when casting. An enchanted gem or rune that can be used by anyone relies on "natural recharging". And while it does not take the effort of a mage to recharge, it will usually take much longer between uses to re-absorb from the ambient magic.
If an enchanted gem or token is taken to an area with no magic they will be quickly drained and will have to be re-created by a skilled mage.