The stereotype of an artist today is someone starving in a garrett, probably wearing a beret, maybe smoking a cigarette and drinking absinthe. This stereotype probably derives ultimately from the opera La Bohème (a great opera, but not a particularly informative work of social history). Were medieval artists like this?
No! (You knew I'd say that, didn't you.)
Medieval artists were not free-spirited individuals creating art in solitude and following their own muse (and starving), but rather professional artisans, employed (and paid) to produce art. The distinction between art and architecture which we make really didn't make sense. The majority of medieval art was religious, and a lot of it was produced for churches.
The people who employed artists were often religious leaders (bishops, abbots) but might be wealthy lay people, especially in the late Middle Ages. Art included illustrations in Bibles and religious books (called illuminations), statues big and small, crucifixes and other liturgical objects, carvings on the fronts of churches or on the capitals at the top of pillars, and wall paintings.
The above image is a capital at the top of a pillar, showing the story of David and Goliath.
There were standard ways of depicting certain people and events; Saint Peter, for example, was always shown with enormous keys. But the artists had a great deal of latitude in how they worked with the standard expectations. Artists were given a lot of room for creativity, so that even though a particular image might look at first glance a lot like others, the individual artist would make it his (or hers).
It used to be believed that medieval artists worked anonymously, but in fact the best ones had excellent reputations, and artists often signed their works. A lot of these signatures have been worn off over the centuries, but if you look carefully at the tympanum over the front door of Autun cathedral, you will see the words "Gislebertus hoc fecit" right under Christ's feet, meaning, "I Giselbert made this." Giselbert was rightly proud of his work.
(The above image may be too small for you to see the words, but they're there. See detail.)
Art was valued both for its beauty and for the value of the materials as well as the quality of craftsmanship. Illuminations in Bibles, for example, often included gold leaf.
During the Renaissance (which is really another term for the late Middle Ages in Italy, as I have discussed elsewhere), artists started to produce portraits of lay people, which had not really been found earlier, other than a few kings. Again, the artists were commissioned (and paid). They often worked in ateliers, with masters and apprentices. The great majority of Renaissance art, however, was religious.