Hedge Witches, or Hedges for short, are Magicians who practice magic without having a formal education in a Magical school. They partially consist of magicians who have been expelled or simply did not make the cut at Brakebills University's entrance exam (or various other magical schools).
Hedges practice self-taught magic known as "Hedge magic". To the uninitiated, real spells and magical knowledge is hard to come by and thus, they scour the internet and various places in search of materials. Such locations may be sketchy and full of experimental or homemade spells that are not particularity strong, or well made, or even well copied. This can be dangerous, thus Hedges tend to find each other to form safe houses where they teach and share magical knowledge.
Hedge Witches are out in the real world, piecing together scraps of spells gleaned from hours spent scouring the internet and other public sources, some even stealing from each other or doing unmentionable favors for unscrupulous Magicians. Because of this, Hedge Witches are generally looked down upon by classically trained Magicians. They operate out of so-called Safehouses and focus on collecting spells and gaining a higher star level so they can grow their power and knowledge of magic.
Hedge Witches are competitive, which while beneficial in an established setting possibly hinders their growth; two safehouses 5 miles apart don't typically share spells. Becoming an actual functioning Magician in the seedy world of DIY Magic is highly unlikely, and genuinely skilled Hedge-witches are few and far between.
Some Hedge Witches learn magic together in safehouses. Knowledge of magic is ranked with small blue seven-pointed stars, some with numbers inside them. The more stars, or higher the numbers, the higher the rank. The highest rank a hedge witch can reach is level 250. Very few have reached this rank and it is near the same level of a classically trained Master Magician.