Magitech
(This page explains the theory behind magitech. For the applications of magitech, read the technology page.)
Magitech is a blanket term for any machine that can cast a spell. In modern times, most household appliances - lights, ovens, washing machines, and so forth - use spells to function.
Magitech is created using magesilver, a material that absorbs and conducts mana. Every magitech device contains a caster: a piece of magesilver shaped into a magic circle. When a current of mana runs through the caster and fills in all its glyphs, the magic circle will activate and produce its effect, the same way as it would if a human had cast the spell.
Enchanted Items
Before the invention of reliable mana power sources, magitech was heavily limited. A machine had to be powered by either the ambient mana in the atmosphere (in which case it would be weak and impossible to turn off) or by a human user (in which case the user might just as easily learn to cast the spell themself without a machine's help). These simple devices are collectively known as enchanted items, and many people do not consider them magitech at all, in the same way that most people don't consider a knife to be technology.
Still, not having to focus on casting a spell is often a convenient advantage. Some household lights and heaters are enchanted items powered by ambient mana, which could be put away or disassembled when not needed. The most commonly seen enchanted items are weapons and protective clothing, due to a large market of rich adventurers. The user can send mana into them to activate small effects to help them in battle.
Modern Magitech
High-power magitech became possible with the invention of mana catchers: enormous machines containing tons of magesilver wires, arranged into lunglike branches for maximum surface area. They pull mana from the surrounding atmosphere and funnel it into the bottom of the machine, where it is distilled into its pure liquid form.
In Orlis, mana catchers are run by the city, and the mana collected is then distributed to the citizens as a public utility much like water or gas. Most cities in Wywick lack the infrastructure to do this, and you can instead find smaller mana catchers in the homes of individuals who can afford it. After the mana is distilled, it can then be used to power magitech devices either through wires or packaged in batteries. Most portable magitech devices (e.g. mobile phones) have miniature mana catchers inside them as well, to supplement the battery and make it lose charge more slowly.
Whatever the power source, mana flows from it and into the caster. The casting of the spell releases the mana directly into the atmosphere, so there's no second wire that leads back to the power source.
Casters in more complicated magitech can be made up of many magic circles attached to each other with complicated systems of if-glyphs that dictate when and how they activate in relation to each other. Since there is some leeway on the exact shape of a magic circle, most magitech circles are actually hexagonal to conserve space; if you cracked open a portal phone, you would find an intricate honeycomb pattern of tiny magic circles inscribed on its circuit boards.
Keys
Magitech excels at straightforward conversions of mana into energy or motion - air conditioning, kitchen appliances, and railed transportation were all invented soon after the discovery of magesilver. However, mana flows only a little faster than water, so things that require immediate and dramatic state changes are much more difficult. For example, if you turned on a magitech light, it would take several seconds for the mana to reach the caster and the light to flicker on. Things like guns and digital displays therefore took much longer to create.
During the war 8 years ago, Orlis scientists reverse-engineered a technology known as keys from First Age magitech, which made quick state changes much easier. A key links a magic circle with a physical condition (as opposed to another magic circle, like an if-glyph): the position of a switch relative to the circle, the color of a panel in front of it, and so forth. A magic circle with a key is always active, but only actually produces its effect when the keyed condition is met. Keys increase the size of magic circles and make them burn mana even when they're inactive, so they are a lot more expensive to run than non-keyed circles of similar power, but they also open up a lot of new possibilities.
Although any magitech device can be keyed to make it more convenient to use, keyed light switches and kitchen appliances haven't been widely adopted yet due to logistical issues and the increased mana requirements; if someone's house lights turn on immediately, it means they've got a passion for home renovation and money to burn. Keys have been incorporated into a variety of new communication and computing technology, though, and now pretty much every household on the planet has a handy portal phone.